In 1976, Don­ald War­ren—a so­ci­olo­gist from Oak­land Uni­versity in Michigan who would die two dec­ades later without ever at­tain­ing the rank of full pro­fess­or—pub­lished a book called The Rad­ic­al Cen­ter: Middle Amer­ic­ans and the Polit­ics of Ali­en­a­tion. Few people have read or heard of it—I learned of it about 30 years ago from the late, very ec­cent­ric pa­leo­con­ser­vat­ive Samuel Fran­cis—but it is, in my opin­ion, one of the three or four books that best ex­plain Amer­ic­an polit­ics over the past half-cen­tury.

While con­duct­ing ex­tens­ive sur­veys of white voters in 1971 and again in 1975, War­ren iden­ti­fied a group who de­fied the usu­al par­tis­an and ideo­lo­gic­al di­vi­sions. These voters were not col­lege edu­cated; their in­come fell some­where in the middle or lower-middle range; and they primar­ily held skilled and semi-skilled blue-col­lar jobs or sales and cler­ic­al white-col­lar jobs. At the time, they made up about a quarter of the elect­or­ate. What dis­tin­guished them was their ideo­logy: It was neither con­ven­tion­ally lib­er­al nor con­ven­tion­ally con­ser­vat­ive, but in­stead re­volved around an in­tense con­vic­tion that the middle class was un­der siege from above and be­low.

War­ren called these voters Middle Amer­ic­an Rad­ic­als, or MARS. “MARS are dis­tinct in the depth of their feel­ing that the middle class has been ser­i­ously neg­lected,” War­ren wrote. They saw “gov­ern­ment as fa­vor­ing both the rich and the poor sim­ul­tan­eously.” Like many on the left, MARS were deeply sus­pi­cious of big busi­ness: Com­pared with the oth­er groups he sur­veyed—lower-in­come whites, middle-in­come whites who went to col­lege, and what War­ren called “af­flu­ents”—MARS were the most likely to be­lieve that cor­por­a­tions had “too much power,” “don’t pay at­ten­tion,” and were “too big.” MARS also backed many lib­er­al pro­grams: By a large per­cent­age, they favored gov­ern­ment guar­an­tee­ing jobs to every­one; and they sup­por­ted price con­trols, Medi­care, some kind of na­tion­al health in­sur­ance, fed­er­al aid to edu­ca­tion, and So­cial Se­cur­ity.

On the oth­er hand, they held very con­ser­vat­ive po­s­i­tions on poverty and race. They were the least likely to agree that whites had any re­spons­ib­il­ity “to make up for wrongs done to blacks in the past,” they were the most crit­ic­al of wel­fare agen­cies, they re­jec­ted ra­cial bus­ing, and they wanted to grant po­lice a “heav­ier hand” to “con­trol crime.” They were also the group most dis­trust­ful of the na­tion­al gov­ern­ment. And in a stand that wasn’t really lib­er­al or con­ser­vat­ive (and that ap­peared, at least on the sur­face, to be in ten­sion with their dis­like of the na­tion­al gov­ern­ment), MARS were more likely than any oth­er group to fa­vor strong lead­er­ship in Wash­ing­ton—to ad­voc­ate for a situ­ation “when one per­son is in charge.”

If these voters are be­gin­ning to sound fa­mil­i­ar, they should: War­ren’s MARS of the 1970s are the Don­ald Trump sup­port­ers of today. Since at least the late 1960s, these voters have peri­od­ic­ally co­alesced to be­come a force in pres­id­en­tial polit­ics, just as they did this past sum­mer. In 1968 and 1972, they were at the heart of George Wal­lace’s pres­id­en­tial cam­paigns; in 1992 and 1996, many of them backed H. Ross Perot or Pat Buchanan. Over the years, some of their is­sues have changed—il­leg­al im­mig­ra­tion has re­placed ex­pli­citly ra­cist ap­peals—and many of these voters now have ju­ni­or-col­lege de­grees and are as likely to hold white-col­lar as blue-col­lar jobs. But the ba­sic MARS world­view that War­ren out­lined has re­mained sur­pris­ingly in­tact from the 1970s through the present.

In ex­plain­ing Trump’s as­cent, most polit­ic­al ana­lysts have ig­nored the role of this dis­tinct ideo­logy. In­stead, they have ten­ded to at­trib­ute his suc­cess to his per­son­al style. In Au­gust, for in­stance, The New York Times con­cluded that Trump’s co­ali­tion was “con­struc­ted around per­son­al­ity, not sub­stance.” Polling ex­pert Nate Sil­ver has in­sisted that Trump’s ap­peal, in con­trast to that of Bernie Sanders, is not re­lated to the policies he es­pouses. “Trump,” he writes, “is largely cam­paign­ing on the force of his per­son­al­ity.”

This ex­plan­a­tion isn’t en­tirely wrong: Trump’s per­son­al­ity—his out­spoken­ness, his dis­dain for polit­ic­al-cor­rect­ness, his show­man­ship, his repu­ta­tion as a bil­lion­aire deal-maker—has cer­tainly con­trib­uted to his polit­ic­al suc­cess. In­deed, a force­ful per­son­al­ity—a ver­it­able man on a white horse—is what Don­ald War­ren found MARS to be look­ing for.

But it would be a mis­take to as­sume that Trump’s sup­port­ers are drawn to him simply be­cause of his per­son­al­ity or be­cause, like Ben Car­son and Carly Fior­ina, he is a polit­ic­al out­sider. What has truly sus­tained Trump thus far is that he does, in fact, ar­tic­u­late a co­her­ent set of ideo­lo­gic­al po­s­i­tions, even if those po­s­i­tions are not ex­actly con­ser­vat­ive or lib­er­al. The key to fig­ur­ing out the Trump phe­nomen­on—why it arose now and where it might be headed next—lies in un­der­stand­ing this world­view.

American populists have long con­foun­ded the di­vi­sion between left and right. Left pop­u­lists like Wil­li­am Jen­nings Bry­an and Huey Long sought to cham­pi­on “the people” against Wall Street or big busi­ness; right pop­u­lists like Pitch­fork Ben Till­man and Ger­ald L. K. Smith at­tacked wealthy elites but fo­cused their ire equally—or more so—on minor­it­ies and im­mig­rants. Yet all these pop­u­lists had something in com­mon: They saw them­selves as de­fend­ing the middle class against its en­emies.

Perot was closer to the left-wing tra­di­tion of pop­u­lism: He de­nounced the Gen­er­al Mo­tors ex­ec­ut­ives he had battled and the re­volving-door lob­by­ists in Wash­ing­ton who rep­res­en­ted for­eign firms. Wal­lace and Buchanan leaned more to the right; but just as Perot wasn’t really a lib­er­al, they didn’t eas­ily fit as con­ser­vat­ives. Wal­lace fought in­teg­ra­tion, but he also com­plained that “the present tax laws were writ­ten to pro­tect the Rock­e­fellers, the Fords, the Carne­gies, and the Mel­lons.” Buchanan de­fen­ded “Middle Amer­ica” against “at­ro­cit­ies” com­mit­ted by an “in­va­sion” from the south of “il­leg­al ali­ens”; yet he also foresaw “a battle between the hired men of the Money Power who long ago aban­doned as quaint but use­less old ideas of na­tion­hood—and pop­u­lists, pat­ri­ots, and na­tion­al­ists who want no part of [Clin­ton ad­min­is­tra­tion Treas­ury Sec­ret­ary] Robert Ru­bin’s world.”

Trump is squarely with­in the Wal­lace-Buchanan tra­di­tion. Speak­ing on be­half of the “si­lent ma­jor­ity,” he blames un­doc­u­mented im­mig­rants for urb­an vi­ol­ence (“A lot of the gangs that you see in Bal­timore and in St. Louis and in Fer­guson and Chica­go, you know they’re il­leg­al im­mig­rants”) and for driv­ing down wages and rais­ing wel­fare costs. But he has also ac­cused hedge-fund spec­u­lat­ors of “get­ting away with murder” on their tax bills, while the middle class is be­ing “decim­ated” by taxes; and he has chided in­sur­ance com­pan­ies for get­ting rich off of the Af­ford­able Care Act.

It isn’t just pop­u­lism that un­der­girds the MARS world­view, however; an­oth­er key com­pon­ent is na­tion­al­ism. Wal­lace saw him­self as de­fend­ing Amer­ica against its en­emies at the United Na­tions. He op­posed most for­eign aid. He presen­ted him­self as “a man who would lead Amer­ica to new great­ness” and would “stand up for Amer­ica.” Perot and Buchanan, who ran for of­fice after Amer­ica’s trade sur­plus had turned in­to a grow­ing de­fi­cit, ad­voc­ated na­tion­al­ist eco­nom­ic po­s­i­tions that dis­tin­guished them from most Re­pub­lic­an politi­cians and from “new Demo­crats” like Bill Clin­ton. Perot warned that the North Amer­ic­an Free Trade Agree­ment was cre­at­ing a “gi­ant suck­ing sound” that would draw jobs away from the United States; Buchanan charged that NAF­TA and the Gen­er­al Agree­ment on Tar­iffs and Trade were de­signed for the be­ne­fit of “the mul­tina­tion­al cor­por­a­tions and the fin­an­cial elite.”

Trump has gone even fur­ther on trade. He has prom­ised to rene­go­ti­ate or junk NAF­TA and to slap a pun­it­ive tax on Chinese im­ports. In his an­nounce­ment speech, he pledged to “bring back our jobs from China, from Mex­ico, from Ja­pan, from so many places. I’ll bring back our jobs, and I’ll bring back our money. Right now, think of this: We owe China $1.3 tril­lion. We owe Ja­pan more than that. So they come in, they take our jobs, they take our money, and then they loan us back the money, and we pay them in in­terest, and then the dol­lar goes up so their deal’s even bet­ter.”

He also ar­gued, in his 2011 book, for get­ting “tough on those who out­source jobs over­seas and re­ward com­pan­ies who stay loy­al to Amer­ica. If an Amer­ic­an com­pany out­sources its work, they get hit with a 20 per­cent tax.” And he has prom­ised to end cor­por­ate tax “in­ver­sions,” whereby a com­pany moves its of­fi­cial headquar­ters to a tax haven in or­der to avoid U.S. taxes. Re­cently, I asked Buchanan wheth­er he thought Trump’s pop­u­lism and eco­nom­ic na­tion­al­ism were in line with what he and Perot had ad­voc­ated. “Trump is a bil­lion­aire, but he gets it,” Buchanan told me. “It’s a very pop­u­list ap­peal and it works.”

The fi­nal ma­jor ele­ment of the Wal­lace-Perot-Buchanan-Trump world­view has to do with lead­er­ship and gov­ern­ment—and like oth­er parts of their agenda, it’s com­plic­ated. All four, like many con­ser­vat­ive politi­cians of the past 50 years, harshly cri­ti­cized Wash­ing­ton. Wal­lace charged that the fed­er­al gov­ern­ment “was run by pointy-headed bur­eau­crats who can’t park a bi­cycle straight.” Buchanan called for dis­mant­ling four Cab­in­et de­part­ments. Perot pop­ular­ized the term “grid­lock” in de­scrib­ing Wash­ing­ton polit­ics. Echo­ing his pre­de­cessors, Trump has de­nounced the “total grid­lock” in­side the Belt­way. “Our lead­ers are stu­pid, our politi­cians are stu­pid,” he said dur­ing the first de­bate, adding later that even­ing: “We have people in Wash­ing­ton who don’t know what they are do­ing.”

But in subtle and not so subtle ways, these four men have also en­dorsed a more power­ful ex­ec­ut­ive at the top. Wal­lace, who had thor­oughly dom­in­ated Alabama’s polit­ics, was seen by crit­ics as a po­ten­tial “dic­tat­or.” Buchanan, who had served Richard Nix­on through Wa­ter­gate, touted the leg­acy of his former boss. Perot called for plebis­cites to de­term­ine key eco­nom­ic policies—which would have had the ef­fect of es­tab­lish­ing a dir­ect re­la­tion­ship between the people and the pres­id­ent, thereby by­passing Con­gress. For his part, Trump en­vis­ages the pres­id­ent act­ing as the “deal-maker in chief.” In a 1982 es­say, “Mes­sage from MARS,” Sam Fran­cis, who would later ad­vise Buchanan dur­ing his cam­paigns, called this out­look “Caesar­ism”; it is also re­min­is­cent of Lat­in Amer­ic­an pop­u­lists like Juan Per­on.

In­deed, none of these can­did­ates ne­ces­sar­ily op­posed big gov­ern­ment. Wal­lace was the can­did­ate of right-wing ra­cists, but he also wanted to in­crease So­cial Se­cur­ity be­ne­fits and make the tax sys­tem more pro­gress­ive. Perot was ob­sessed with de­fi­cits and debt, but he wanted to bal­ance the budget by rais­ing taxes on the rich. He also favored a pub­lic-private part­ner­ship to en­sure uni­ver­sal ac­cess to health care. Buchanan and Trump re­jec­ted calls to privat­ize or elim­in­ate So­cial Se­cur­ity and Medi­care. “We’ve got So­cial Se­cur­ity that’s go­ing to be des­troyed if some­body like me doesn’t bring money in­to the coun­try,” Trump said in his an­nounce­ment speech. “All these oth­er people want to cut the hell out of it. I’m not go­ing to cut it at all; I’m go­ing to bring money in, and we’re go­ing to save it.” Trump also prom­ises to fix aging bridges and air­ports. “I want to re­build our in­fra­struc­ture,” he says.

In view of Trump’s stands on gov­ern­ment and eco­nom­ics, his Re­pub­lic­an crit­ics have charged that he is not really a con­ser­vat­ive. In Na­tion­al Re­view, Jo­nah Gold­berg wrote that “no move­ment that em­braces Trump can call it­self con­ser­vat­ive.” That’s prob­ably true; and it was also true of Trump’s pre­de­cessors as MARS stand­ard-bear­ers.

In 1968, Wallace, run­ning on the Amer­ic­an In­de­pend­ent Party tick­et, won five South­ern states and 46 elect­or­al votes; in early Oc­to­ber 1968, he was still get­ting as high as 20 per­cent of votes na­tion­ally. Run­ning as a Demo­crat in 1972, he won primar­ies in six states, in­clud­ing blue-col­lar Michigan and Mary­land—and was poised to hold the bal­ance of power in the con­ven­tion un­til he was shot and forced to stop cam­paign­ing in May.

In the spring of 1992, Perot an­nounced he was run­ning as an in­de­pend­ent, and by early June, he was lead­ing both Pres­id­ent George H. W. Bush and Demo­crat­ic chal­lenger Bill Clin­ton in the polls with 38 per­cent. Un­der at­tack from in­vest­ig­at­ive journ­al­ists and op­pos­i­tion re­search­ers, Perot pulled out of the race in Ju­ly, but then reentered on Oc­to­ber 1. He even­tu­ally got 19 per­cent of the vote—the best show­ing for a third-party can­did­ate since 1912.

Buchanan ran a protest cam­paign in the Re­pub­lic­an primary in 1992 and got 38 per­cent of the vote against Bush in New Hamp­shire. In 1996, he ran a more ser­i­ous cam­paign and shocked even­tu­al nom­in­ee Bob Dole by tak­ing the Louisi­ana and Alaska caucuses, and then the New Hamp­shire primary. This sum­mer, Trump, of course, astoun­ded polit­ic­al ob­serv­ers, in­clud­ing me, by out­polling his Re­pub­lic­an rivals.

Who are the voters who fueled these cam­paigns? If you take ac­count of changes over the years to the edu­ca­tion­al level and oc­cu­pa­tion­al pro­file of the Amer­ic­an work­force, there is a straight line between the MARS who flocked to Wal­lace and those who have backed Perot, Buchanan, and Trump. In 1968, Wal­lace’s greatest sup­port was among white, male, middle-in­come, and lower-middle-in­come work­ers and small farm­ers who had not gone to col­lege. In Septem­ber 1968, at a time when over a fourth of Amer­ic­an work­ers be­longed to uni­ons, an in­tern­al AFL-CIO sur­vey found that Wal­lace was backed by a third of uni­on voters. In 1972, Wal­lace also re­ceived strong sup­port from blue-col­lar private-sec­tor uni­ons in states like Michigan.

In the 1992 elec­tion, Perot did best among middle-in­come voters and those with some col­lege, as op­posed to those with only a high school edu­ca­tion or those with col­lege de­grees—that is, the very voters who were mostly likely to be feel­ing squeezed from both above and be­low. In the 1996 New Hamp­shire Re­pub­lic­an primary, Buchanan did best among ex­actly the same voters.

Demo­graph­ic­ally, Trump seems to be at­tract­ing the 2015 equi­val­ent of these voters. In na­tion­al polls of Re­pub­lic­ans, and polls of Iowa caucus­go­ers, Trump’s sup­port is sig­ni­fic­antly stronger among those who do not have col­lege de­grees and earn less than $100,000. In a Quin­nipi­ac na­tion­al poll re­leased on Septem­ber 24, Trump does bet­ter among voters without col­lege de­grees; and most tellingly, voters without col­lege de­grees are much more in­clined than voters with col­lege de­grees to think he “cares about the needs and prob­lems of people like you.” By con­trast, voters with col­lege de­grees are much more likely than those without col­lege de­grees to be­lieve that the three oth­er can­did­ates named in the sur­vey ques­tion—Jeb Bush, Carly Fior­ina, and Ben Car­son—em­path­ize with them. (Most of those voters without de­grees prob­ably did at­tend some col­lege. Ma­jor polls of­ten don’t re­cord sep­ar­ately the small num­ber of Re­pub­lic­ans who haven’t at­ten­ded col­lege at all.)

The es­sen­tial world­view of these Middle Amer­ic­an Rad­ic­als was cap­tured in a 1993 post-elec­tion sur­vey by Stan­ley Green­berg, which found that Perot’s sup­port­ers were more likely than Clin­ton’s or Bush’s to be­lieve that “it’s the middle class, not the poor who really get a raw deal today” and that “people who work for a liv­ing and don’t make a lot of noise nev­er seem to get a break.” They agreed with Clin­ton voters that cor­por­a­tions don’t “strike a fair bal­ance between mak­ing profits and serving the pub­lic,” but they also agreed with Bush voters that “too many of the poor are try­ing to get something for noth­ing” and that “we have gone too far in push­ing equal rights for dif­fer­ent groups in this coun­try.”

There has been no sim­il­ar polling of Trump’s sup­port­ers, so all one can rely on are crowd re­ac­tions and in­ter­views. Re­cently, I at­ten­ded two Trump ral­lies: one at a high school aud­it­or­i­um in Hamp­ton Falls, New Hamp­shire, where the line to get in stretched all along the side of the build­ing and in­to the park­ing lot, as if it were the first night of a box-of­fice block­buster; the oth­er at the 20,000-seat Amer­ic­an Air­lines Cen­ter in Dal­las. The Dal­las rally too was packed; it was filled with rauc­ous sup­port­ers wear­ing red Trump T-shirts and “Make Amer­ica Great Again” caps. The crowd was over­whelm­ingly white and roughly equally male and fe­male. Even though the rally was held at 6:00, right after work on a week­day, I coun­ted ex­actly two men in the audi­ence who were wear­ing suits and ties—and one of them, whom I in­ter­viewed, had come to ac­com­pany his aging moth­er, a Trump back­er, and was him­self lean­ing to­ward Jeb Bush.

At both ral­lies, Trump’s rail­ing against il­leg­al im­mig­ra­tion got ap­plause. But so did his at­tacks on Chinese cur­rency ma­nip­u­la­tion and cor­por­ate ex­ec­ut­ives who ship jobs over­seas. Al­most all of the ap­prox­im­ately 30 people I in­ter­viewed at these events men­tioned Trump’s op­pos­i­tion to il­leg­al im­mig­ra­tion, his de­fi­ance of polit­ic­al-cor­rect­ness, and the strong lead­er­ship they ex­pec­ted him to bring to the pres­id­ency. Yet al­most every­one also cited his eco­nom­ic na­tion­al­ist stands. “He is about get­ting jobs back. I have two kids that can’t find jobs. The jobs are go­ing to Mex­ico,” one wo­man in New Hamp­shire told me. Said a young Trump sup­port­er in Dal­las, who was also a uni­on mem­ber, “I don’t like the idea of tax dol­lars be­ing used to ship jobs out to Lat­in Amer­ica or East­ern Europe.” (The pre­vi­ous month, an of­fi­cial of a large in­ter­na­tion­al uni­on had told me that if his uni­on held a ref­er­en­dum on who to en­dorse for pres­id­ent, Trump would prob­ably win.) An­oth­er young Trump sup­port­er in Dal­las chided me for ask­ing ques­tions that seemed de­signed to pi­geon­hole him polit­ic­ally. “You are mak­ing as­sump­tions about left and right,” he said. “The me­dia puts us in one or the oth­er. It’s not a good way to define people.”

At the Dal­las rally, I was sup­posed to meet up with a tea-party act­iv­ist whom I had in­ter­viewed for an art­icle two years ago, but we nev­er found each oth­er. So I cor­res­pon­ded with him af­ter­ward about why he was back­ing Trump. Asked about Trump’s eco­nom­ic na­tion­al­ism, he wrote back: “I do not have any prob­lems nor does my wife with any of Trump’s na­tion­al­ist po­s­i­tions. We are all for them. It is long past time that we get our fair share from the Chinese, Ja­pan­ese, Mex­ic­ans, and oth­ers.” I also asked him about Trump’s pledge to pro­tect So­cial Se­cur­ity and Medi­care. His reply? “I do not want Trump to mess with So­cial Se­cur­ity oth­er than to put a pro­pos­al in front of Con­gress on how to fix it and Medi­care for the long run.”

There is, as it turns out, con­sid­er­able over­lap between the tea-party world­view and Middle Amer­ic­an Rad­ic­al­ism. (Here, I would dis­tin­guish between loc­al tea-party groups, which line up with the MARS out­look, and na­tion­al busi­ness front or­gan­iz­a­tions that took on the tea-party mantle, which do not.) In June 2014, for in­stance, tea-party act­iv­ists in great­er Rich­mond led the fight to de­pose House Ma­jor­ity Lead­er Eric Can­tor. Tea-party can­did­ate Dav­id Brat charged Can­tor not only with sup­port­ing am­nesty for il­leg­al im­mig­rants but with back­ing “the crooks up on Wall Street.” Today, not sur­pris­ingly, Trump leads among self-iden­ti­fied tea-parti­ers. In an early Septem­ber CNN / ORC poll, Trump was backed by 41 per­cent of re­spond­ents who said they sup­por­ted the tea party—double that of the next choice.

To see where all of this may be headed, it’s help­ful to con­sider why bursts of Middle Amer­ic­an Rad­ic­al­ism oc­cur at cer­tain mo­ments. Sev­er­al con­di­tions have, in the past, proved cru­cial. One is a wide­spread sense of na­tion­al de­cline. That was cer­tainly the case in the late 1960s and early 1970s, when the United States was mired in Vi­et­nam; in the early 1990s, when the United States faced a pro­trac­ted eco­nom­ic slow­down; and again from 2008 to the present. When the sense of doom has lif­ted, as it did when the Clin­ton boom began in the spring of 1996, the MARS vot­ing bloc has gradu­ally weakened.

The second con­di­tion is pro­nounced dis­trust of the lead­er­ship in Wash­ing­ton. Wal­lace’s MARS were angry about the fed­er­al in­ter­ces­sion in race re­la­tions. In the early 1990s, many con­ser­vat­ive voters felt be­trayed that Bush had broken his prom­ise not to raise taxes, while oth­ers were en­raged by the ad­min­is­tra­tion’s seem­ing in­dif­fer­ence to the re­ces­sion and the grow­ing clout of for­eign lob­by­ists in Wash­ing­ton. That sense of dis­trust com­pletely lif­ted after Septem­ber 11, 2001, when Amer­ic­ans saw the na­tion­al gov­ern­ment as their pro­tect­or. But it has re­turned dur­ing the Obama years: Middle Amer­ic­an Rad­ic­als saw Obama’s re­cov­ery pro­gram and his health care plan as a sop to Wall Street and the poor—which the middle class would have to pay for.

Un­til this sum­mer, Middle Amer­ic­an Rad­ic­als lacked a lead­er—someone to play the cata­lyz­ing role that Wal­lace and Perot had played dec­ades ago—and they were furi­ous at the Re­pub­lic­an con­gres­sion­al lead­er­ship, which they had helped bring in­to power in 2010 and again in 2014, for fail­ing to re­verse Obama’s policies. (One Trump sup­port­er at the Dal­las rally de­scribed House Speak­er John Boehner and Sen­ate Ma­jor­ity Lead­er Mitch Mc­Con­nell to me as “a bunch of trait­ors.”) Then along came Trump—the lead­er the MARS move­ment had been miss­ing.

But can he suc­ceed where Wal­lace, Perot, and Buchanan fell short? Can a MARS can­did­ate ac­tu­ally win the White House? One hes­it­ates at this point to of­fer any pre­dic­tions, but my sus­pi­cion is that Trump will fail like the oth­ers. There is, of course, his volat­ile per­sona, which seems likely to cause self-in­flic­ted wounds (just as Perot’s did in 1992). But the big­ger lim­it­ing factor for Trump is that there are only a cer­tain num­ber of MARS in the coun­try: They con­sti­tute maybe 20 per­cent of the over­all elect­or­ate and 30 to 35 per­cent of Re­pub­lic­ans. That was enough to al­low Trump to lead a crowded GOP field. But as the field nar­rows, he will have dif­fi­culty main­tain­ing his lead un­less he can ex­pand his ap­peal bey­ond the MARS. And it will be hard to do that without threat­en­ing his base of sup­port.

It there­fore seems un­likely that we will end up with a MARS pres­id­ent in 2016 or bey­ond—es­pe­cially since their per­cent­age of the elect­or­ate is con­tinu­ing to shrink. Still, that doesn’t mean MARS will ne­ces­sar­ily fail to have a polit­ic­al im­pact. After all, tea-party act­iv­ists—a group Har­vard so­ci­olo­gist Theda Skoc­pol es­tim­ated at 250,000 dur­ing Obama’s first term—have had a de­cis­ive in­flu­ence on the bal­ance of power in the House of Rep­res­ent­at­ives since 2010.

The size of the MARS role go­ing for­ward will ul­ti­mately de­pend on wheth­er Amer­ic­ans be­lieve their na­tion is in de­cline and wheth­er they think the politi­cians in Wash­ing­ton are cap­able of, or even in­ter­ested in, re­vers­ing that de­cline. Ron­ald Re­agan dis­pelled fears of de­cline and was thus able to ab­sorb many former Wal­lace sym­path­izers with­in the GOP. Fol­low­ing Bill Clin­ton’s re­pu­di­ation by voters in Novem­ber 1994, he moved to the polit­ic­al cen­ter and was able to lim­it (though by no means elim­in­ate) the ef­fect of middle-class rad­ic­al­ism. Both Re­agan and Clin­ton be­nefited, however, from a grow­ing eco­nomy and ap­par­ent suc­cesses over­seas. Will the next ad­min­is­tra­tion en­joy the same good for­tune? With the world eco­nomy still in the doldrums, an on­go­ing crisis in the Middle East, and a po­lar­ized and para­lyzed Wash­ing­ton, I doubt it. What’s most likely is that Middle Amer­ic­an Rad­ic­al­ism will keep sim­mer­ing, un­til it finds a new cham­pi­on and boils over once again.

This article originally appeared in National Journal.