There is no obvious reason for Obama to root for socialist candidate François Hollande in the next French presidential election, where the first round will take place April 22. Indeed, Obama even authorized part of his latest videoconference with Nicolas Sarkozy to be shown on French TV, with the U.S. president saying "I admire the tough battle you're waging." Since he was elected in 2007, Sarkozy has been a good ally, loudly proclaiming his proximity to the United States, bringing France back into the integrated military command of NATO, maintaining a hard line on Iran, competently driving the G20 process and leading from the front in Libya.

Admittedly, there also have been irritants. Sarkozy thought Obama's steps to move towards full nuclear disarmament were naive. Last year, he supported Palestinian aspirations at the UN General Assembly and at UNESCO, with no coordination with Washington. In January, he abruptly announced that French soldiers would leave Afghanistan in 2013 rather than on the agreed 2014 date. And he dragged his feet on Obama's revamped missile-defense scheme. But if Sarkozy is not the reflexive Atlanticist in the mold of Tony Blair some are making him out to be and is seen by the White House as unpredictable and impetuous, at least he is a known quantity. So why should Obama prefer the devil he doesn't know?

For starters, he may have no choice. Sarkozy is a dogged campaigner, and he staged an impressive comeback in the polls during the month of March (before the Toulouse terrorist attacks, not as a result of them). But he has been trailing François Hollande from the start, not so much for the first round of the election as for the run-off, by 8 percentage points and sometimes more. Sarkozy may still make it on May 6, but it is a big challenge to be reelected in the context of the euro crisis and rising unemployment, as other EU leaders will attest. So when one adds the appetite of the energized Left—which lost the last three presidential elections since 1995 but won almost all other polls since 2007—and the enduring mistrust between "Sarko" and public opinion, this really looks like an election for François Hollande to lose.

That is what the socialist candidate has calculated, running a low-key campaign as the anti-Sarko with no fireworks. In terms of image and narrative, this means looking calm where Sarkozy is seen as agitated, thoughtful where Sarkozy is seen as impulsive and moderate where Sarkozy is seen as excessive. In terms of foreign policy, this means rejecting any sudden shift of direction and being predictable to others. No drama and no surprise: the Obama recipe.

That is at least the message delivered by Hollande’s personal emissaries, president of the Brittany region Jean-Yves Le Drian and president of the senate Jean-Pierre Bel, to the Obama administration in March: what you see is what you get. The rest of Hollande's message went this way: the moderate Left in France and in the United States, although distinct on many counts, have natural affinities. We know President Obama is in a difficult reelection campaign. We wish him well and don't want to put him in difficulty, so we will work out our potential disagreements as constructively as possible.

If François Hollande gets elected, continuity should prevail on most of the issues that are central to current Franco-American relations. There would be no disagreement on Iran, on which Hollande has announced he would maintain the tough line followed since Jacques Chirac, or on Syria, on which Right and Left are indistinguishable. Hollande said he would launch an assessment of the French full reintegration of NATO military command, of which he disapproved but made it clear he would not reverse that decision and leave again. Sarkozy and Hollande's defense budgets would be the same, with both going slightly down to make an effort at reducing the deficit but with no dramatic drop in capacity. On a few issues—like relations with Turkey—the Franco-American dialogue might actually be easier than with Nicolas Sarkozy.

Potential Clashes

There are a few areas where Hollande's position could be a problem for Obama—and here, the calendar doesn't help. If elected on May 6, Hollande will be officially proclaimed president around May 17, just before the G8 meeting at Camp David and the NATO summit in Chicago, and he may wish to go to Berlin before the G8. This means he will have very little time to negotiate on the more contentious foreign-policy points of his electoral program.

Hollande has announced that he would start the withdrawal of French combat troops from Afghanistan as soon as he gets in power in order to complete the process by the end of 2012—that is, a year earlier than Sarkozy and two years earlier than the schedule agreed to at NATO in Lisbon. (Secretary Panetta declared that American forces would transition from combat missions to a training mission in 2013.) More recently, however, Hollande seemed to insist less on the 2012 target and stress more the importance of coordinating with allies. Simple logistical considerations might facilitate an agreement (extracting the French forces and their hardware from dangerous zones like the Kapisa province will take longer than six months anyway), but the potential for a clash is certainly present.

The same problem exists with missile defense, on which many French, especially on the Left, have misgivings for reasons of cost and strategy. While theater missile defense makes good sense in the eyes of all analysts, the larger ballistic-missile shield, even under its Obama version (the phased adaptive approach), leaves them skeptical since it is seen in Paris as needlessly jeopardizing the legitimacy of nuclear deterrence. In budget terms, Paris can afford its own independent nuclear force de frappe or invest massively in the next steps of missile defense, but not both. Here again, however, most negotiations will take place before the elections with the Sarkozy administration, and there would be little time, should Hollande win, to change direction before NATO meets in Chicago. Breaking the NATO consensus, on the other hand, would be costly and could project the wrong image on the international scene, which is why the most serious French-American discussion on this issue would probably take place later on.

The Troubled Euro Zone

By far the most important transatlantic issue for Obama—and the most potentially damaging for him—is the euro crisis. Since May 2010, Obama has tended to side with Nicolas Sarkozy rather than Angela Merkel in favor of more active support of debt-ridden countries, whether through a larger firewall or a more assertive intervention by the European Central Bank, including more robust measures to stimulate growth—even if that meant delaying fiscal consolidation. This Obama-Sarkozy convergence, however, has not prevented Chancellor Merkel from winning the argument in favor of a new treaty, the Fiscal Compact, which imposes new disciplines on euro-zone members but doesn't do much in terms of promoting growth.

This is the one issue on which Hollande might be more appealing to Obama than Sarkozy, who must now stick to the December agreement he helped conclude with Merkel. Hollande has more flexibility. When the deal was concluded, Hollande criticized the Fiscal Compact and declared he would renegotiate it, saying it imposed welcome upgrades in discipline but didn't answer the main challenge facing Europe, that of stimulating economic activity in order to grow out of debt problems. Hollande was blamed for putting the new treaty in jeopardy, but in the early spring, worried observers, investors and many European governments agreed that only more stimulus would save Europe from a virtuous death.

While Angela Merkel threw her weight behind Sarkozy's reelection and even broke with regular practice in refusing to receive the socialist candidate, Germany’s SPD party—whose support she needs to ratify the treaty with a two-thirds majority in the Bundestag—declared itself in agreement with François Hollande. If elected, Hollande could negotiate, for example, an additional protocol concerning Continental growth, which might be supported by other European partners and the Obama administration because it increases the chances Europe will not fall into a deep recession—and endanger U.S. recovery.

Hollande, however, will still face a true leadership challenge to convince other conservative partners like David Cameron and Mariano Rajoy—used to dealing with Sarkozy—to come along. Upon his election in May 2007, Sarkozy managed to turn around the fate of the European Constitution in a few months by negotiating a revised version which became known as the Lisbon Treaty.

Should he be elected, the biggest international challenge for François Hollande, after the early tests of Camp David and Chicago, will be finding his place on the new European scene and bring about a new Franco-German consensus on growth. But if he plays his cards well in the first few weeks, he may find he has a friendly supporter in the White House.

Justin Vaïsse is the director of research for the Center on the United States and Europe and a senior fellow in Foreign Policy at the Brookings Institution. An adjunct professor at the Johns Hopkins School of Advanced International Studies, he is the author of many articles and books including, most recently, Neoconservatism: The Biography of a Movement.