On April 20, President Donald Trump announced on Twitter a plan to “suspend immigration” in light of the coronavirus pandemic, setting off a policy scramble that resembled the 2017 effort to carry out his campaign calls for a “shutdown of Muslims entering the United States.” By the time he sent that tweet, his administration had already spent weeks trying to rename the new coronavirus the “Chinese virus”—despite the fact that implicitly blaming Asians and Asian Americans for the spread of the virus has led to a dramatic increase in violent hate crimes.

Given Trump’s track record, some Americans rightly feared that he would use the pandemic to rationalize discriminatory policies and fuel nativist rhetoric. Trump’s insistence on labeling the coronavirus as foreign echoes past nativist moments when diseases such as cholera, polio, and smallpox were linked to immigrants. So what can we learn from this, and how can Americans respond? In “Resisting the Call of Nativism,” we assess democracies’ experiences with nativism to offer advice—and warnings—for dealing with politicians who suggest some citizens are less equal than others.

Nativists are not simply voters who favor reducing immigration or desire an official national language; those are legitimate questions on which well-meaning people might disagree. Rather, nativists believe nationality is inherently based on race, ethnicity, or religion. This understanding of who counts as a “real” citizen leads them to propose second-class citizenship for some groups and to try to keep members of those groups out of the country. Nativists reject the full democratic participation of groups they deem undesirable, treating their policy preferences and beliefs as illegitimate. For example, Trump’s July 2019 tweets telling four Congresswomen to “go back [to the…] places from which they came” made a direct appeal to nativism, suggesting the Congresswomen are not real Americans because they are not white.

Of the group of primary voters who propelled Trump to the Republican nomination, 77 percent thought one must be Christian to be “truly American” and 47 percent believed one must be of European descent. Yet while nativists have been gravitating to right-wing parties, their beliefs place them squarely in the category of swing voters. In Austria and France, nativist parties found support when they combined generous welfare for the ingroup with tough policies to reduce rights and benefits for second-class citizens and keep less desired groups out. Of all the Republican voting blocs in the United States, Trump’s nativist core professed the greatest support for redistribution and safety net programs, and a majority had previously voted for Democrats.

The challenges nativist politicians pose have vexed democracies around the world. In Australia, in Canada, and across Europe, mainstream parties often collaborate with nativists to gain power, believing they can temper the extremes. Instead, nativists either take over the mainstream party or beat it in elections. When opposing parties try to ignore nativism and change the subject, it doesn’t work; the only way to keep nativists from controlling the political agenda is to condemn and reject nativism. When this happens, nativist candidates still attract votes but can’t usually take over major parties or control policy.

In weaker democracies where votes are cast on ethnic or religious lines, voters expect politicians to deliver more to their group and less to others. Sanitation, policing, even clean water begin to depend on which groups voters belong to—fueling inequality and making countries more prone to violence and corruption. The racial inequities in health, clean air, hospital care, and death rates made obvious by the coronavirus show that the United States starts farther down this path than many peer democracies. It is past time to reverse course.

First, politicians across the political spectrum need to condemn nativism in word and deed. Parties confronting nativist candidates should expand on the treatment Republicans meted out to Senate candidate Roy Moore in Alabama: deny funding, refuse support, and endorse—or even fund—opponents. Nativists who get to Congress anyway should be denied major committee assignments and legislative votes or cosponsors—the tactics Republicans used to handle then U.S. representative Ron Paul due to his iconoclastic views.

Of course, none of this can happen as long as one party depends on nativists for votes. In Canada and Australia, parties have turned away from nativism after embracing it, and in the United States, Democrats in the 1960s decided to give up the votes of the segregationist South to create a new coalition based on the demographic future. Republicans who want the United States to remain a pluralist democracy based on values, not skin color or religion, need to retake their party. They could start by reviving the 2012 autopsy conducted after Mitt Romney’s presidential election loss and expanding their base to make common cause with conservative minority voters. They may need to rebrand, or perhaps even rename, the party. But that would be a small price to pay for protecting all Americans equally and honoring the country’s core values.

Rachel Kleinfeld is a senior fellow in the Democracy, Conflict, and Governance program at the Carnegie Endowment for International Peace. John Dickas is a visiting lecturer at Sciences Po Paris. They are the authors of “Resisting the Call of Nativism: What U.S. Political Parties Can Learn From Other Democracies.”