"I am in this race because I believe I am the strongest candidate... and the strongest president," Hillary Clinton said in her victory speech tonight. Hillary has certainly said things in this campaign that she clearly doesn't actually believe (see the gas tax holiday). But I think this reason, more than any other--more than her campaign debt, or the millions of women invested in her candidacy, or even the Clintons' sense of political entitlement--explains why she stays in the race, even in the face of crushing delegate math. (The pro-Obama Jed Report now calculates that Hillary would need to pick up a ludicrous 93 percent of the remaining available delegates, assuming the self-declared "Pelosi Club" superdelegates who have said they will back the pledged delegate winner stick to that promise.) She may be deluding herself, but Hillary really seems to believe that Obama neither deserves nor can win the White House. And I suppose if that's how she truly feels then it's hard to blame her for staying in the race, so long as she doesn't damage him beyond repair.
The trouble is that, even if her victory speech didn't question Obama's qualifications, Hillary's mere presence in the race on a night like this likely diminishes Obama's standing. It hardly makes him look strong when Hillary is on stage talking about being the best president and Obama is nowhere to be seen. Or Karl Rove is declaring, as he did on Fox News, that "West Virginia is a state that likes regular people. It can smell an elitist coming... somebody who's looking down their nose at them a hundred miles away." Hillary may believe that she is more electable. But if her highest priority is for Democrats to win the White House, a purely rational calculation, given the odds against her, would have led her to drop out last week and campaign with Obama in West Virginia, helping him to avoid tonight's embarassing storyline. (TNR's Josh Patashnik makes a smart and plausible case here for why Obama should be grateful Hillary stayed in. But if she'd dropped out and actively promoted him in WV, things might have been different.)
Ultimately the reason she doesn't, I think, is that Hillary is simply and utterly convinced she is the most electable, most qualified candidate. That may be arrogant, it may be a fantasy. But if it's something she really and truly believes--and I think it is-it must be awfully hard to walk away from.