Not all Democrats are in a swoon over Barack Obama, but even many of those who aren't believe he has a better chance than Hillary Clinton to beat John McCain in the general election. But I'm not so sure. The very factors that work in his favor against Mrs. Clinton during the nomination fight might work against him in the general election. Let me explain.

Both racism and sexism are still powerful forces in the United States, but they aren't the same. Sexism is more deeply rooted and harder to shake. After all, men live with women from the start, and their attitudes about women are formed early. Some sexual stereotypes are not only accepted, but acceptable, and one of those is that women are less likely to be effective leaders than men. In contrast, racism, while prevalent, is generally seen as unacceptable and something to be uprooted. Black men were given the right to vote 53 years before women and their median income is higher.

All of this works in Mr. Obama's favor during the nomination fight. Democrats, particularly men, are more likely to vote for a black man than a white woman, and feel virtuous doing so. Mrs. Clinton is in the usual dilemma faced by ambitious women. She is seen as too calculating or too emotional, too rigid or too malleable, too liberal or too conservative. The harsh scrutiny of everything about her except what matters -- her policies and record -- tells me that many people justify their sexism by finding this particular woman objectionable.

But if Mr. Obama comes up against Mr. McCain in the national contest, I think the tables could turn. The alternative to Mr. Obama would then be a white man, not a woman. Latent racism would make itself felt, particularly among the all-important independent voters.

Mrs. Clinton might actually do better against Mr. McCain in the general election for the simple reason that women constitute over half the electorate. Among Democrats, women -- who have a long history of championing the causes of disadvantaged groups other than their own -- are now split between Mr. Obama and Mrs. Clinton. But if a woman faced a white man in the general election, they might very well unite behind Mrs. Clinton.

There is another reason Mrs. Clinton might do better in November. As she herself has pointed out, Republicans have thrown everything they have at her. She can't be swift-boated, because she already has been. There would be no surprises.

Mr. Obama has enjoyed a remarkably easy ride with both the media and the Republicans, who seem as dazzled by him as the Democrats. But that will quickly change if he is nominated. An adoring media can turn on a dime, and you can be sure that Republicans will search through every detail of his life to find something to throw at him.

That will be all the more devastating because Mr. Obama has allowed something of a personality cult to grow up around him. Many voters, swept up in it, have suspended their critical faculties -- temporarily. But when reality catches up, as it always does, or the hero is found to have flaws, whether real or imaginary, the fall from the pedestal can be as dizzying as the adulation that put him there in the first place.

Mr. Obama's unity theme could also backfire. He has said he wants to "bring the country together and stop the bickering" and "change the tone in Washington." But the problem has not been that Democrats are too confrontational, but that they've caved in again and again to President Bush's disastrous policies. Does Mr. Obama really think that a change in tone will dissuade the people who think that water-boarding and warrantless surveillance are OK, or make the super-rich happy to give up their tax cuts? There are important principles at stake here, many of which have been compromised too much already.

Either Mr. Obama or Mrs. Clinton would be a much better president than the one we have now (it's hard to imagine worse) or the warrior who aspires to succeed him. The two espouse much the same policies, and their voting records in the Senate are virtually identical. But I confess that I prefer Mrs. Clinton precisely because she is a woman. After 218 years and 43 male presidents, isn't it about time that the majority of the population was represented in the White House? And isn't it just possible that women would rally to that cause in a national campaign against the Republicans?