Words could come back to haunt Barack Obama.
Not "monster," the insult that political adviser Samantha Power lobbed at Hillary Clinton, which forced Power's embarrassing resignation Friday.
Rather, Obama's oft-stated promise to take the high road during the campaign could become a liability as his duel with Clinton intensifies in the next few weeks and months, say political pundits.
Last December, Obama said he "did not want to see research that is involved in trying to tear people down personally. If I found out that somebody is doing that, they will be fired. And I have been absolutely crystal clear about this, and I have been clear about this for a very long time."
That vow leaves him in a difficult position: If Obama goes on the attack, he could be accused of hypocrisy; if he remains above the fray, he could be overrun by attacks and appear weak, much like John Kerry was hurt by taking too long to respond to attack ads from the Swift Boat veterans.
"For him, the trick is going to be to find a way to make a contrast [between Obama and Clinton] in a way that is grounded in hope," says Democratic strategist Steve McMahon.
"He has to figure it out in a way that is more consistent with the tone of his campaign. When your campaign is grounded in changing politics, you don't have quite as much room to operate."
Since Tuesday night's election results in which Clinton won crucial votes, with her television ad featuring sleeping children and a red phone ringing in the middle of the night likely contributing to her win, Obama has ramped up his attacks.
His aides accused Clinton of choosing to "align herself with Sen. McCain," and adviser Susan Rice said it's not possible to gain national security experience "merely by being married to a commander in chief."
Yet Obama maintains he won't give up his promise to fight clean, telling reporters Tuesday night that he would not "change the tone of our campaign" or "do things that I'm not comfortable with."
That vow, exemplified by his campaign's decision to accept Power's resignation, may hurt him against the Clintons, who have plenty of experience on both sides of a dirty fight, says Si Sheppard, professor of political science at Boston University.
"He's trying to maintain his position that this is a campaign of ideas, and setting the bar high for his team but that may give her the initiative. Look at Michael Dukakis. His political mastermind John Sasso was held accountable for negative campaigning, and was forced to dump him and that hurt him because Sasso was quite savvy."
The Clinton campaign has also asked some campaign allies to step down when their personal attacks went over the line: New Hampshire state chairman Billy Shaheen noted Obama's drug use as a teenager and two Iowa field organizers who sent out e-mails falsely claiming that Obama was a Muslim.
Yet her campaign did not punish fundraiser Bob Johnson, who also referred to Obama's drug use.
Clinton communications director Howard Wolfson denied any contradiction, telling reporters in a conference call that Johnson "is a supporter of ours, but he is not a senior policy adviser. … I don't mean to minimize his importance. But he is not part of the daily campaign life in the way that Samantha Power has been."