COLUMBIA, S.C. — Bill Clinton is running again. For what, exactly, isn't clear.
Watch: He's stalking the stage in South Carolina, as he did in New Hampshire and Iowa — a microphone in one hand, a wagging finger in the air, eyes wide open, the lip strategically bitten.
Applause rings out as he ticks off his greatest hits — a budget surplus, a growing stock market, more jobs, safer streets.
"Nobody's figured out how to deal with this," said Larry Sabato, the director of the Center for Politics at the University of Virginia. "The voters don't know, the press doesn't know, and frankly the Clintons don't know, either."
In a presidential election year that's notable for shattered rules, the high visibility of the former president's efforts on behalf of his wife, New York Sen. Hillary Clinton, may the biggest rule-breaker of all.
He's given speeches criticizing media coverage of rival Sen. Barack Obama. In Nevada he suggested caucus rules were purposely tilted against his wife, arguing the issue with a reporter.
In South Carolina, he hinted that Obama's support was based on race. ("That's why people tell me Hillary doesn't have a chance of winning here," he said.)
He claimed he suffered a "hit job" from the Obama campaign — and that his wife had been unfairly criticized.
"When I was running, I didn't give a rip what anybody said about me," he told a rally. "But if you love somebody and think that they'd be good, it's harder."
He's campaigned alone and by her side, standing behind her or off-stage. He's argued, joked, promoted her resume, her positions, defended his own record, turned red in anger and taken shots at critics.
And just as opinions about Bill Clinton as president are deeply polarized, so are the reactions to his role as campaign surrogate-in-chief.
"He is out there for his wife," Clinton supporter James Carville said on NBC last week. "And Bill Clinton is enormously popular with the Democrats in this country. They like seeing him out there, they respond very well to him and he's going to be in the middle of this campaign."
"The former president is pathological about preserving his own place in the spotlight," liberal columnist William Greider wrote Wednesday. "He can't stand it when he is not the story, and, one way or another, he will make himself the story."
For the record, Mrs. Clinton is happy to have Mr. Clinton's help.
"Everybody needs to take a deep breath," she told CBS Friday. He "gets excited, gets really passionate about making the case for me."
It isn't altogether unusual for former presidents to take part in presidential campaigns as private citizens. Harry Truman, for example, publicly opposed John Kennedy's campaign for the Democratic nomination in 1960.
And candidates' spouses sometimes have been campaign issues: Think Nancy Reagan, Betty Ford or — Hillary Clinton.
But no one has ever campaigned for a return to the White House as a spouse and former president, a situation that's angered, befuddled and concerned Democrats watching the race unfold.
"The way he goes about it, what he says, how he says it, the tone he uses, he's not the average spouse now," said Arizona Gov. Janet Napolitano, an Obama supporter. "We need to conduct this campaign in a way that allows us to come back together."
"I have no respect for him for the remarks that he's been making," said Bennie Bayard, a South Carolina retiree at an Obama rally there.
Clinton partisans insist he does more good than harm.
"We have seen the Obama campaign confronting Bill Clinton, attacking Bill Clinton," said Clinton campaign spokesman Howard Wolfson. "Attacking the former president, questioning his veracity, confronting him...is not what's going to bring this party together."
Others point out that Elizabeth Edwards and Michelle Obama are campaigning for their spouses, John and Barack, aggressively; at times, both spouses' words have taken on an edge of their own.
"When power is confronted with real change, they will say anything," Michelle Obama said last week, echoing a South Carolina radio ad that targets Hillary Clinton directly.
"What she's saying is she's willing to sell special access to the government. Just send a check," Elizabeth Edwards said about Hillary Clinton last fall.
But even some neutral Democrats say Bill Clinton, as a former president, should be especially careful. South Carolina Rep. James Clyburn, a key African-American power broker in the state, said last week that the former president should "chill."
Sen. Ted Kennedy, D-Mass., and Rep. Rahm Emanuel, D-Ill., also reportedly have offered similar advice; so far, the Clinton campaign has agreed only occasionally.
The Democrats' worry: Bill Clinton could become the target in a Hillary Clinton general election campaign, particularly given their stormy White House years.
"Bill Clinton is a mixed blessing ... if she's the nominee, he'll become more 'mixed' than 'blessing,'" Sabato said.
Clinton fatigue will be "absolutely" a factor, he added. "Already I'm hearing more and more about 28 years of either a Bush or a Clinton on the ticket."
Republicans appear ready to make Clinton an issue.
"The idea of Bill Clinton back in the White House with nothing to do is something I just can't imagine," presidential candidate Mitt Romney said in a Florida debate Thursday.
Other Democrats worry that the former president's rhetoric will tarnish his reputation. On Thursday, Missouri Sen. Claire McCaskill, a Democrat, called Clinton's efforts "demeaning."
"I don't think we ought to get into this food fight," said Rep. Emanuel Cleaver, D-Mo., co-chair of Hillary Clinton's Missouri campaign. "When it's over — and it will be over — I want President Clinton for the next 25 years to be a major political influence in this country."
But if Bill Clinton is worried about his legacy, or his immediate impact on his wife's campaign, he's shown no evidence of that.
In last week's often angry Democratic debate, Obama complained about the former president's statements.
"I'm here, he's not," Hillary Clinton snapped.
"I can't tell who I'm running against sometimes," Obama responded.
The exchange made supporters on both sides nervous.
"I kind of liked seeing Barack and Hillary fight last night," Clinton told South Carolina voters. "They're real people. Neither one of them is supposed to be this wind-up doll who's supposed to behave a certain way. ...I think it's exciting."
(Helling, of the Kansas City Star, reported from Kansas City. Matt Stearns reported from South Carolina.)