Watch John Kerry grapple with the issue of Iraq, and you see a careful man trying to say as little as possible, torn between the desire to offer a way out of the predicament and the cliches about "staying the course."

Look at the Democrats flirt with the possibility of enticing John McCain to be their vice-presidential candidate, and you get the sense of a political party that isn't eager to challenge President Bush's military intervention in Iraq. McCain, after all, has generally been at least as hawkish as Bush on Iraq; indeed, in the 2000 presidential campaign, he was the preferred candidate of the neoconservatives precisely because he was more willing than Bush to support U.S. military intervention overseas.

What's the trouble with the Democrats on foreign policy? Why have their candidates seemed so conflicted? Why haven't they been able to come up with a clear, coherent alternative to the Bush administration's approach? Does Kerry have a vision of America's role in the world that will unify the party?

To understand the Democrats' performance in the current campaign, and to get a sense of the legacy that Kerry will bring with him into office if he wins the election, one has to look at the different constituencies, the preoccupying issues and the conflicts within the party over the past 30 years. Their recent history has made the Democrats instinctively leery of leaving too much distance between themselves and the Republicans on foreign policy issues, lest they be tarred once again with accusations of being weak on national security.

It is too early to know yet exactly what groups, individuals or schools of thought will emerge as the dominant influences on Kerry's foreign policy. After all, at this point four years ago, virtually no one would have guessed where Bush was headed. In May 2000, Dick Cheney was a Halliburton executive helping Bush choose a running mate, and Donald Rumsfeld was barely visible in the campaign. The predictions were that if the Republican candidate won, his foreign policy would be little more than a rerun of the first Bush administration's.

It is clear that whatever direction Kerry takes, he will have to navigate among a variety of interests within the Democratic Party. Organized labor is concerned about job losses and outsourcing. The business/Wall Street wing of the party -- which was in ascendance during the Clinton administration -- favors policies that will promote exports and growth. At the grass-roots level, the party includes many activists whose intellectual origins date back to the Vietnam era; they tend to oppose the use of military force and to seek constraints upon American power overseas. At the elite level, the Democrats' foreign policy ranks include many officials who favor an assertive U.S. role in international affairs, including the use of force when necessary; they believe that the United States is and should be -- as Bill Clinton and former secretary of state Madeleine Albright liked to say -- the "indispensable nation." The two major parties, then, are more similar to one another at the top than among their rank and file.

There is, however, one striking difference between the Democratic and Republican foreign policy elites: their career paths. Virtually all the leading members of the current Republican administration rose to the top after serving in the Pentagon; the Bush team includes two former secretaries of defense, one former chairman of the Joint Chiefs of Staff and a host of other former Pentagon officials. By contrast, virtually none of the leading Democratic foreign policy hands are oriented, by career or by outlook, toward the Department of Defense.

Over the past three decades, Democrats have had fewer opportunities to oversee U.S. foreign policy than Republicans have had. Since the watershed election of 1968, there have been only two Democratic presidents, Jimmy Carter and Bill Clinton. In the last transition of power in January 2001, even the most experienced Democratic foreign policy hands -- such as Clinton national security adviser Sandy Berger, U.N. ambassador Richard Holbrooke and Albright -- left office with fewer years in government than many of the members of the incoming Bush team, even before the latter group started another Republican administration.

Of course, experience isn't everything. In foreign policy as in anything else, it can sometimes get in the way. The Republicans' many years of service during the Cold War may have hampered their ability to come to grips with the world after 9/11. (Indeed, some Democrats are now making precisely such a claim; the Republicans, they say, were too focused on conventional states at the expense of paying attention to transnational organizations like al Qaeda.) One could also argue that the Republicans' long record of experience counts for less when it has led to intense divisions within their own ranks, such as the ideological disputes between neoconservatives and realists, or the conflicts over military intervention between, say, Cheney and Secretary of State Colin Powell.

The Democrats have had their own deep internal divisions. After Vietnam, the liberal wing of the party sought to rein in military spending and impose restrictions on American intelligence operations. Some hawks abandoned the party; the Republicans portrayed the Democrats as weak on national defense and won three presidential elections in a row. Not until the Cold War had ended and national security had diminished as a political issue did the Democrats win the White House again.

But in the 1990s, the Democrats became progressively more willing to support the use of military force. The 1991 Persian Gulf War proved to be a turning point. In the run-up to the war, the overwhelming majority of Senate Democrats opposed military action to reverse Saddam Hussein's invasion of Kuwait. Several cited predictions that war against Iraq would cause large numbers of Americans to be brought home in body bags. After Operation Desert Storm ended with relatively few American casualties, some Democrats began to reconsider. Then, in the Clinton years, a new constituency emerged within the party -- one that endorsed the use of force for humanitarian purposes. This was largely a response to two events: the ethnic cleansing in Bosnia, which prompted a delayed response, and the genocide in Rwanda, in which the Clinton administration did not intervene.

By October 2002, when President Bush sought approval for a congressional resolution authorizing new military action against Iraq, a majority of the Democratic senators voted to support it.

Kerry's career reflects these larger shifts within the Democratic Party. The former antiwar activist, who first attracted attention as the public face of Vietnam Veterans Against the War, voted with the Democratic majority against the Gulf War in 1991. In 2002. he voted with the party's majority to authorize war with Iraq.

Thus, in political terms, the past year of violent upheaval in Iraq caught Kerry, and other elite Democrats like him, leaning in the wrong direction. They had in recent years become more willing to countenance assertions of American military power, but the Iraq conflict has produced a grass-roots resurgence of the sort of antiwar sentiments that animated their early careers.

Furthermore, the past few weeks' revelations of torture and other abuses at Abu Ghraib prison have reawakened among the Democrats the larger, Vietnam-era questions about the legitimacy of American power. "Abu Ghraib is a windfall for the antiwar folks," mourns Will Marshall, the president of the Progressive Policy Institute. Marshall, as a leader of the centrist New Democrat movement that backed Clinton, has for years sought to steer the Democratic Party toward a policy in favor of a strong military and an active U.S. role abroad. "There's pressure on Kerry now to become much more vocal and to abandon his support for staying and winning in Iraq," Marshall says. "So far, he's wisely resisted that pressure."

Caught in the crosscurrents, Kerry seems to have decided to challenge Bush not on whether he should have gone to war with Iraq, but on how he did so. Kerry hasn't ventured to say that the United States made a fundamental mistake in going to war; instead, he has said that Bush mismanaged the operation. "The argument they [Kerry and his aides] are making against Bush is more a 'competence' argument than a 'change direction' argument," says Bob Borosage, a Marshall adversary who has long pressed within the party for limits on U.S. defense spending and a redirection of resources to domestic programs.

The core of this argument is that the United States should rely more on multinational institutions and alliances to obtain greater international legitimacy for its actions overseas. However, leading Democrats would also reserve the right of the United States to use force abroad, even unilaterally. "A Democratic administration will need to reaffirm the United States' willingness to use military power -- alone if necessary -- in defense of its vital interests," wrote Berger in the current issue of Foreign Affairs. "But it will have no more urgent task than to restore America's global moral and political authority, so that when we decide to act we can persuade others to join us."

As much as any Democratic leader today, Kerry has been buffeted by the crosswinds inside his party. He knows the tangled legacy of Vietnam. He opposed the use of force overseas at a time when most of his fellow Democrats did; he supported military intervention when a majority of the Democrats in Congress did likewise. "Like most senators, he hasn't reached the point of formulating a policy that you can sustain, so that when things are going bad, you can hold to it. He hasn't done it on Iraq," says Leslie Gelb, former president of the Council on Foreign Relations and a Defense Department official in the Carter administration.

That may work in the Senate, but it won't be possible on the campaign trail or in the White House. It will be up to Kerry and the people around him to chart the course of a possible Democratic administration. He may have to choose between the competing views in his own party about America's role as the world's leading military power. So far, he doesn't seem to have made up his mind. The voters, and the party, await his choice.

Author's e-mail: jmann@csis.org

James Mann is senior writer in residence at the Center for Strategic and International Studies and author of "Rise of the Vulcans: The History of Bush's War Cabinet" (Viking).