Tonight's Real Debate: Obama Vs. Bill Clinton?

If the headlines inspire the questions at tonight's Democratic debate in South Carolina, expect former President Bill Clinton to come up nearly as often as Hillary Clinton, the one who's actually a candidate.

Bill Clinton's actions, both during his administration and on the campaign trail on behalf of Hillary, have become a central point of contention in the Democratic race, and Obama recently added fuel to the fire when he suggested that Clinton failed to "change the trajectory" of the country while president, but Ronald Reagan did.

An angrier, edgier side of the president "from a place called Hope" has emerged in recent weeks, starting with his comment just before the New Hamsphire primary comparing Obama's views on Iraq – or his whole campaign, depending on who you listen to – to a "fairy tale." The former president has also accused Obama's campaign and its supporters of dirty tricks ahead of Nevada's caucuses, and in general, the man known as "Big Dog" has taken on the role of attack dog for his wife's campaign.

Tonight's debate will likely keep the Clintons vs. Obama story in the headlines for at least a few more days, barring a "burying the hatchet" moment like we saw at the previous debate that brought an effective end to a racially charged back-and-forth over the role of Martin Luther King Jr. and Lyndon Johnson in the passage of civil rights legislation.

But such peacemaking is unlikely, given Obama's comments today on Bill Clinton's aggressive posture. Speaking to ABC News, the Illinois senator said Clinton "has taken his advocacy on behalf of his wife to a level that I think is pretty troubling," and said he would "directly confront Bill Clinton when he's making statements that are not factually accurate."

It's hard to prognosticate how the battle will play out. Obama has cut into Hillary Clinton's support among black voters, who are key to his hopes of winning South Carolina's Saturday primary, the last before Super Tuesday. But Bill Clinton is still beloved by many in the African American community – taking him on could be a bridge too far for Obama. However, Clinton's original "fairy tale" comment outraged many prominent African Americans – keeping that in the media might hurt Hillary Clinton among black voters. That doesn't even take into account the Feb. 5 contests, where "Clinton fatigue" – or desires for a Clinton restoration – could be a factor. If voters see an angry Bill Clinton as an unpresidential Bill Clinton, Obama might benefit.

While the principals involved seem to be spoiling for a fight, much of the Democratic establishment seems to want it over with. Newsweek's Jonathan Alter notes that one of the party's elder statesmen, Sen. Edward Kennedy, and Rep. Rahm Emmanuel, a former Clinton aide who helped orchestrate the Democratic takeover of Congress in 2006, have both leaned on the former president to tone down his rhetoric. Influential South Carolina Rep. James Clyburn has also called for an end to hostilities.

Tonight's debate should be a pivotal moment for a dispute that, so far, has done nothing but escalate. Bill Clinton won't be on the debate stage, but his presence will undoubtedly be felt.