Watching the Israeli and Palestinian leaders trudge to Washington for one more peace summit, one might wonder why President Obama invited them. Why should the president invest his prestige in an effort that looks so unpromising?

Palestinian President Mahmoud Abbas is desperate for a peace agreement but so politically weak that he probably cannot make one. And Israeli Prime Minister Netanyahu is politically strong now but probably does not want an agreement because he has good reason to believe it could cause his fall from power.
And while Palestinian stances on most of the divisive issues have not changed in some time, the current Israeli government takes positions that are more hard line than those of its predecessors over the past decade.
Obama's decision to host the talks and push the Palestinian president into participating makes sense only in light of his need to perform two specific tasks: to test Netanyahu's intentions and to show that he and the Israeli prime minister are on the same page before the midterm elections.
That might sound paradoxical, but for Netanyahu it is a chance to make good on the pledge he made on July 8 to "confound the critics and the skeptics" once he had a Palestinian partner for direct talks.
Netanyahu certainly played the role of the statesman well at the start of this week's events. Despite the killing of four Israeli civilians in the West Bank on the eve of talks, he voiced his "respect" for the Palestinian "desire for sovereignty" and said Israel was prepared to go "a long way in a short time."
Working closely with Netanyahu now also serves Obama's domestic political agenda; it will take some of the air out of a pre-electoral campaign by Republicans to portray Obama, and by association other Democrats, as unfriendly to Israel.
The stated U.S. goal of reaching a peace agreement in one year also seems almost unbelievably naive in the face of years of failed efforts. But this time frame says something about the thinking of U.S. negotiators.
The next year will be the best time for Obama to invest political capital in the negotiations. As of fall 2011, he will be absorbed in another presidential campaign season and what will help him is a success -- not necessarily a final agreement but at least a negotiating process that appears to be going somewhere.
Another reason for the one-year time frame is that U.S. officials know the Palestinian government headed by President Abbas is living on borrowed time. Abbas is well past his electoral mandate, which expired in January 2009. He has no control over Gaza. which Hamas has ruled since a takeover in 2007. And he has little in the 80 percent of the West Bank that is still under Israeli military rule.
He and his government are able to stay in power because of diplomatic and financial support from the United States and Europe. This situation is not sustainable indefinitely.
It was undoubtedly out of concern for Abbas that President Obama criticized in his September 1 statement "those who insist that this is a top priority and yet do very little to actually support efforts that could bring about a Palestinian state," an oblique reference to Arab states, including Saudi Arabia and the United Arab Emirates, that have cut their donations to the Palestinian Authority recently.
As direct talks begin, there are several possible scenarios.
The most pessimistic is that talks fall apart over the issue of Israeli settlement construction in the West Bank later this month, when Netanyahu's settlement "moratorium" (not a freeze of all construction but a limit on new housing starts) expires.
The most optimistic is that Netanyahu really does surprise his critics and makes proposals -- for example, on the future borders of a Palestinian state -- that allow negotiations to progress.
The most likely scenario, however, is that talks continue for three to six months without making real headway. They might eventually fall apart because of an external crisis -- such as violence in the West Bank or Gaza, war in Lebanon, an attack on Iran -- or Abbas might withdraw and even threaten to resign from his post.
At that point Obama and his administration would have to decide whether to pull out or to increase their involvement by announcing a U.S. peace plan, for example, and putting pressure on the two parties to accept.
That would be a high-stakes effort and would require extensive diplomacy to build support from Arab and Muslim states, but would show that the United States will not give up without exhausting all possibilities.
In considering such a step, Obama would have to weigh the likely tension with Israel and resulting discomfort in U.S. political circles against the damage to U.S. security interests in the broader Middle East if another failed peace process.