Just two months ago, there appeared no chance that Sen. John McCain could emerge as the Republican nominee for president and little chance that any other Republican could win the presidency in November. Now McCain is the presumptive nominee -- and in most polls, an even bet to occupy the Oval Office next January. Whether he does may depend on whether the Democratic nominee can avoid being tagged as "defeatist" on Iraq.

First, give McCain his due. After a disastrous 2007, he dispatched both Rudy Giuliani and Mitt Romney with relative ease in 2008. Americans respect his record of wartime service and sacrifice. In a country where the past two presidential elections were virtual dead heats and every state but one is winner take all -- and thus "red" or "blue" (not purple) in the context of reaching 270 electoral votes --a McCain presidency today is as likely as any other.

Polls continue to show a majority of Americans believe the war in Iraq has not been worth the cost. But if the reduction in violence we saw in late 2007 continues in 2008, many voters may find plausible McCain's argument that supporting the troop "surge" was the right choice and that he will continue to choose wisely in the future.

In this context, a "future vision" for Iraq may be what matters most with a large swath of American voters in November. McCain's message is simple: He has vowed that the United States will not be defeated in Iraq. He will accuse either Sen. Hillary Clinton or Sen. Barack Obama of "raising the white flag." Clinton and Obama have the more complex rhetorical and substantive argument: explaining why the withdrawal of large U.S. combat units from Iraq -- which they both favor -- does not equate with defeat, but rather is essential to prevailing in the global conflict with radical Islam.

Both Clinton and Obama have struggled on the question of "winning" in Iraq. When asked during a January CNN-sponsored debate whether they were looking to "end this war or win it," each focused on bringing troops home. Neither spoke of winning, or convincingly explained why withdrawing troops from Iraq would actually improve the United States' ability to deal effectively with radical Islam.

It would be risky for either Democrat to assume that voters will accept an approach that fails to be grounded in "winning" -- or fails to explain how troop withdrawals from Iraq will enhance U.S. security. Americans may want to end this war, but they still want a political and military strategy that can win -- or at least one that will not strengthen the appeal of forces dedicated to harming U.S. interests. To win in November, Democrats must explain that the victory the United States seeks -- to prevail in what will be a long war of ideas with radical Islam -- cannot be achieved by the indefinite occupation of Iraq. The longer we stay, the more likely we are to further inflame anti-American passions and mobilize extremists in the region and in Europe.

In short, to "win" in Iraq, and defeat radical Islam more broadly, the United States must have an administration committed to a policy of carefully withdrawing large combat units from Iraq -- as opposed to a policy that envisions a decades-long U.S. troop commitment -- while maintaining a robust military presence in the Middle East, the Persian Gulf and southwest Asia. In addition, we must broaden the canvas of our engagement, focusing most urgently on economic assistance and political reform in the region, along with a resolution to the Israeli-Palestinian conflict.

And Democrats need to find an effective way to communicate these points. Otherwise, McCain's commitment to "stay the course," merged with a vague Nixonian "I'll bring them home with honor," could appeal to voters.

Steve Andreasen, the director for defense policy and arms control on the National Security Council from 1993 to 2001, teaches at the University of Minnesota's Humphrey Institute of Public Affairs.