After a brawling presidential contest in Nevada, Clinton heads into the next battleground of South Carolina with back-to-back victories. For Obama, whose Jan. 3 Iowa victory recedes with time, South Carolina is where he must regain his footing in time for the Feb. 5 megacontest when 22 states will be in competition.
Obama is relying on black voters, who make up more than half of the South Carolina Democratic electorate. Most polls have him leading Clinton in the state. But Clinton has won over many influential black leaders and had led in the state before Obama's Iowa victory established him as a strong contender.
Clinton is likely to continue to be strong among women voters. They gave her a big advantage in Nevada on Saturday.
Women and black voters
Six out of 10 of these attending the state's caucuses were women and nearly half of them backed her, according to a survey of caucus attendees. One in three women supported Obama.
She and Obama split men about evenly. Clinton also prevailed among white voters, getting half of them compared to Obama's one in three. The white vote made up two-thirds of the overall vote.
Black voters heavily favored Obama, but made up fewer than one in five voters.
On to the South
That won't be the case in South Carolina. By Friday night, at a Martin Luther King Jr. banquet in Nevada, Obama already was making his case for black voters to stick with him.
"Sometimes we've got that thing in our heads that says we cannot do something," he said as his largely black audience shouted "Yes!" in response. "We have been told for so long it's not possible. We've got to wait for somebody else to tell us it's possible before we decide it's possible. But let me tell you, I'm here to say it's possible. We're doing it right now. Don't tell me I can't do something!"
That kind of exhortation is likely to continue throughout the week, boosted by Monday's observation of the Martin Luther King holiday.
"Obama has to really take South Carolina to reassert his place in the order," said Scott Huffmon, a political scientist at Winthrop University in Rock Hill, S.C.
The week leading to the Nevada caucuses was one of the most contentious in the Democratic contest so far, and Obama, Clinton and John Edwards head to South Carolina with no sign the race will turn genteel in the South.
Clinton backers went to court in an unsuccessful effort to block special precinct caucuses in Nevada seen as beneficial to Obama. Clinton herself then charged that Obama wasn't steadfast enough against a Nevada nuclear waste site.
Obama backers ran a Spanish language ad calling Clinton "shameless" and said the New York senator "does not respect our people." Then Obama did a Vegas style standup routine that skewered her and got laughs to boot.
The politics of Nevada
Pushed to the front of the presidential calendar by the Democratic National Committee, Nevada was the Democrats' opportunity to tend to a different voting bloc. After competing in white, homogenous Iowa and New Hampshire, Nevada offered a chance to change focus and pay heed to Latino voters, a growing population in the state. That then leads to South Carolina and its large number of black voters.
Along the way, the outreach turned sour. Clinton, trying to make a point about presidential leadership, said it took President Lyndon Johnson to pass civil rights legislation envisioned by Martin Luther King Jr. Obama said the remark suggested to some that Clinton was diminishing King's historic role.
Clinton backer and BET founder Robert Johnson implied that while the Clintons were actively involved in civil rights, Obama was experimenting with drugs and other youthful indiscretions.
During a debate Tuesday in Las Vegas, Clinton and Obama called for a truce on the subject of race.
While that bit of peace held, the campaigns let loose on other fronts.
Late in the week, a federal judge rejected efforts by Clinton backers to halt the use of special precincts to help casino employees caucus along the Las Vegas Strip. Many of the workers are members of the Culinary Workers Union, which backed Obama.
But the judge's ruling did not come soon enough. The union had already fired back, airing an ad in Spanish that denounced Clinton and said "she does not respect our people."
Those were tough words in a contest that was supposed to let the Democratic Party embrace Latino voters, not drive a wedge through them.
Obama, urged by Clinton and Edwards to denounce the ad, did not.
Now comes South Carolina, no stranger itself to fight night politics.