"Let's just saddle up and have an argument," says Bill Clinton, sounding an ultimatum reminiscent of President Bush's "Bring it on." Just as Bush's dare led to more death and destruction in Iraq, Clinton's rallying cry portends more internecine warfare for the Democrats, whose fierce cross-fire is already threatening to weaken the party's chances for victory this fall.

The only thing that could stop the bleeding would be if Barack Obama wins Pennsylvania, an outcome that seems unlikely, given the polls showing Clinton well ahead there. We've seen nastier campaigns before, but this is supposed to be a banner time for Democrats. An unpopular president waging an unpopular war during a time of economic meltdown—all of those factors should help make 2008 the Year of the Democrats. But the Clinton-Obama battle is opening a widening divide over race, class and gender that threatens to short-circuit the opportunity.

Obama's overall poll numbers have withstood the assault on his character and judgment, but the halo has been tarnished. His vulnerabilities on national security and his association with a church that can be caricatured as out of the mainstream may be hard for Clinton to fully exploit in a Democratic primary, but the Republicans will feel no constraints. New polling from the Pew Research Center shows Obama with a "glowing personal image," surpassing Clinton on almost every attribute tested except patriotism. That's where the Rev. Jeremiah Wright comes in, and that's where Obama remains vulnerable, not so much on race but on the anti-American sentiments expressed by his former pastor—sentiments that could be twisted into an attack on the candidate's patriotism. The Republicans are good at that, and the Clintons may yet demonstrate they're not half-bad at it, either. If we see an attack ad featuring Reverend Wright, we'll know Clinton is emptying the arsenal.

President Clinton seems oblivious to the rising negatives for himself, his wife and Democrats in general. He wants to win. This is politics, he's likely thinking, and the hand-wringing doesn't accurately measure what's going on. Others are more concerned. "It's not negative, it's petulant," says a Democratic activist who did not want to be quoted discussing the campaigns. "It's not that they're scarring each other, they're diminishing each other." Obama has more to lose from prolonged skirmishing; his campaign is premised on a promise to end partisan bickering. If he can't rise above it within his own party, how does he bring the country together? Hillary's negatives are already at 48 percent; there's not much room for growth on that score, so she can let it rip. It's what voters expect from her. Hillary backers regularly assail the media for letting Obama get away with saying he's different when his campaign is tearing apart Hillary's character in daily e-mails and conference calls. The argument that he's fighting back, that he can't unilaterally disarm, only increases their fury.

Neither Clinton nor Obama started out as what the pollsters call mobilization candidates. He didn't campaign as the candidate of black aspirations, and Clinton didn't showcase gender. The initial question about Obama was whether he was "black enough" to consolidate African-Americans behind his candidacy in light of their loyalty toward Bill Clinton, whom writer Toni Morrison dubbed the first black president. That changed in part because blacks saw that Obama could win in a largely white state like Iowa, and because Bill Clinton was seen as unfairly injecting race into the debate as he campaigned for his wife in South Carolina. Hillary was "absolutely not running as the woman candidate," says Maren Hesla with EMILY's List, a pro-choice Democratic group working actively for Clinton. Hesla says Mark Penn, Clinton's pollster, believed that as the first woman seriously vying to be commander in chief, "no matter how much she's perceived as strong, that leg of the stool has to be absolutely rock solid." That led to what Hesla calls a "subterranean campaign with women; it was not front and center."

Hillary's sisterhood moment arrived in New Hampshire, when there was a sense among women that she was unfairly under assault. A few tears, a thoughtless offhand remark by Obama ("You're nice enough, Hillary") and a guy flashing a sign that read IRON MY SHIRT, and Clinton was back in contention.

Now polls show that her supporters—read women—are angrier than Obama voters at the prospect of their candidate getting dissed. Gallup reports that 28 percent of Clinton voters would pull the lever for McCain if Obama becomes the nominee while 19 percent of Obama's supporters would bolt if she wins. Pew reported an even higher defection rate for both candidates--prompting Clinton at week's end to reach for some semblance of reconciliation, reminding voters that whatever her differences with Obama, they pale when compared with her differences with John McCain. Can the candidates keep it civil as the campaign rolls into Pennsylvania and beyond? The answer will determine whether 2008 is indeed the Year of the Democrats, or a blown opportunity of historic proportions.

© 2008