As they enter the final rounds of their heavyweight bout for the Democratic nomination, will Sens. Barack Obama and Hillary Clinton be on their best behavior or will they sharpen their jabs at tonight's debate?
The duel between the last two Democratic candidates has gotten more fiery in recent weeks, with heated debates over topics ranging from Tony Rezko to President Reagan, civil rights history to Pakistan and with visual showdowns featuring cold stares and the infamous "snub" after the State of the Union address.
Despite their stated intentions to take the high road, both Clinton and Obama have attacked each other with a passion. The items correcting their opponent's claims on the fact-check sections of their respective Web sites tripled in January compared with the previous month.
At their last debate before Super Tuesday, both candidates will want to make a strong impression without turning off voters, say pundits.
"The tension between the two camps has been escalating and so much of this race hinges on what happens in four days, I would be surprised if it didn't continue to be fairly contentious," said Robert Oldendick, a political science professor at the University of South Carolina.
"They're very similar on the issues and so with those distinctions blurred, it comes down to personality. When it comes down to that, you have to ratchet up the rhetoric to make an impression."
Others expect both candidates to be on their best behavior.
"There's going to be an enormous outburst of civility," said Mitchell Moss, a professor of urban policy and planning at NYU.
"It's been a good old-fashioned family fight and no one wants to raise the temperature any higher. This will be an intense battle, but they're not going to do it in front of the cameras."
And don't expect a repeat of the snub, when Obama turned his back on Clinton while she reached out to shake the hand of Sen. Ted Kennedy, D-Mass., Monday night after the State of the Union, says Molly Epstein, a professor of management communications at Emory University who has studied body language in political campaigns.
"Obama will be extremely sensitive to everything he does, where he rests his eyes, who he turns to," she says.
"It will be in both of their interests to behave in a way that is presidential, looking the other person in the eye no matter how you feel about them."
These nonverbal cues will be a vital part of tonight's debate because most viewers have heard the speeches before.
"We're unlikely to hear any words that we haven't heard before," says Epstein. "We've heard it all at this point so viewers will be looking at facial expressions and body positions to subtle actions like the twitch of an eye like they never have before. Studies show that 98 percent of persuasion is based on what we see, not what we hear."
The clearest recent example of such non-verbal cues was the series of photographs depicting Clinton and Obama after the State of the Union.
While political junkies and pundits analyzed photos of the incident as intently as the Zapruder film, questions remain about Obama's true intentions, Clinton's sensitivity and the media's obsessions.
The snub, or non-snub, took on added weight in light of the increasing rhetoric in the rivalry: "We can be a party that tries to beat the other side by practicing the same do-anything, say-anything, divisive politics that has stood in the way of progress, or we can be a party that puts an end to it," Obama told a crowd of 18,000 at the University of Denver on Monday, reports ABC News' David Wright.
Discussing the key photograph, Obama claimed that he was not turning his back on his chief rival but that he was engaged in conversation with Sen. Claire McCaskill, D-MO.
"I was turning away because Claire asked me a question as Senator Kennedy was reaching for her," he told reporters on his campaign plane. "Senator Clinton and I have very cordial relations off the floor and on the floor."
Obama attributed the mini-scandal to "a lot more tea leaf reading going on here than I think people are suggesting."
And McCaskill backed up his account, explaining to the Los Angeles Times that she had a "ringside seat" for the encounter. She added that the incident was being blown out of proportion by the media, because "everybody's spoiling for a fight, which is the politics of old."
But Clinton seems determined to keep the incident alive, saying "I reached out my hand in friendship and unity and my hand is still reaching out," during an interview with Fox News. "And I look forward to shaking his hand when I see him at the debate in California."
Another photo depicts Obama and Kennedy standing and seemingly looking coldly at Clinton and a female colleague.
That photo could have particular resonance with female voters, especially after the New York chapter of the National Organization for Women released a statement condemning Kennedy for his endorsement of Obama: "Women have just experienced the ultimate betrayal."
Whoopi Goldberg expressed her anger on "The View" on Tuesday, saying, "I was very proud of her for walking up and shaking hands, and going to take Barack's hand, and I have to tell you, I think he was wrong to turn away."
Pundits compared the "snub" to the moment when Clinton's eyes welled up with tears at a coffee shop in New Hampshire earlier this month, but argued that the latest incident would have less of an impact on voters.
While Clinton's tears seemed to gain her some votes on the way to winning the New Hampshire primary, this case "seemed less notable. I can't image this one having much of an impact," says Mel Dubnick, a political science professor at the University of New Hampshire.
"It depends on the media and how it's played out by the press," says Dubnick. "What will happen on the 'Daily Show' tonight? If John Stewart picks up on it and shows the photos, it might have an effect."
Maxine Lucille Fiel, a body language expert who has written extensively about political interactions, says that she tends to believe Obama's account of the incident. "It's clear that he was preoccupied with another conversation," she explains. "I don't think it was really a snub."
Rather, Fiel thinks that Clinton has helped turn the incident into a scandal by discussing her desire to shake his hand.
"I don't know why she would have even brought it up. She seems intent on raising the issue and it's a sign of desperation. .She should let it go. It's a way of saying, 'Look at the old boys club. They're snubbing me.'"
The incident also evoked comparisons to the 1980 convention, when Ted Kennedy's lack of enthusiasm as he shared the stage with nominee Jimmy Carter was palpable to viewers. "That was somewhat similar," says Paul Abramson, the co-author of a series of books documenting presidential and congressional elections. "There was a lot of ill will between those two camps just as there is between these two camps."
"I can't think it will have much of an effect," said Abramson. "It's such a passing thing and so trivial compared to more serious accusations that have been going back and forth that it won't have an impact on female voters."