Barack Obama won Tuesday's Democratic primary in the southern state of Mississippi, racking up another victory over Hillary Clinton in the party's bitter White House race.
US television projections handed Obama his second victory, along with Wyoming's weekend caucuses, since Clinton salvaged her presidential hopes with must-win triumphs in Texas and Ohio last week, setting up a long grind to the end of the primary calendar in June.
With its 33 nominating delegates up for grabs, Mississippi was the last contest in the roller-coaster Democratic race before the huge Pennsylvania primary on April 22.
Exit polls showed a large racial divide in the primary, with massive support for Obama from African-Americans, even as a new race row further soured relations between the two camps.
Black voters made up 48 per cent of voters in the Democratic primary, and 91 per cent of them went for the Illinois senator, according to MSNBC exit poll figures.
Senator Obama's victory was likely to erase the net gain of nominating delegates made by the former first lady with her victories last week, leaving her still trailing by a significant margin.
Heading into Tuesday's primary, Obama had 1,589 delegates while Clinton had 1,470, according to a tally by RealClearPolitics.com.
Neither can reach the winning post of 2,025 delegates, even if Florida and Michigan go ahead with emerging plans to repeat their contests after running afoul of the national party for holding their primaries early.
So the nomination will likely rest in the hands of nearly 800 "superdelegates," Democratic party officials now under enormous pressure from the two campaigns to sway one way or another.
Obama has now won 29 of the Democratic contests, while Senator Clinton has picked up 15, not counting Florida and Michigan, which had their delegates stripped in the scheduling dispute.
The Mississippi exit polls suggested that the nomination fight was causing anger inside the Democratic coalition, a possible problem going into November's general election.
Fifty-five per cent of Obama voters in the southern state said they would not be satisfied if Clinton became the Democratic nominee. Some 72 percent of Clinton voters said they would not be satisfied if Obama ends up as the party's candidate, according to exit polls by Fox television.
In the hotly debated question of which candidate is more ready to serve as president, 53 percent of Democratic voters in the state felt Obama was best prepared, while 43 percent felt Clinton was more qualified.
During the campaign both Obama and Clinton outlined plans to help rebuild communities on Mississippi's Gulf Coast that were obliterated by Hurricane Katrina in 2005.
But the former first lady was already looking past Mississippi with a packed line-up of campaign stops in Pennsylvania, a state with a mix of blue-collar, urban and rural voters whose 158 delegates are up for grabs on April 22.
Republicans were also voting Tuesday.
But as Senator John McCain has already clinched enough delegates to be the party's standard-bearer in the November presidential election, there was little question about the outcome -- projections showed him with 84 percent of the vote.
McCain then can afford to slot in a high-profile trip to Israel, Britain and France next week.
Mississippi primary voting took place on a day when a new race row raged between the camps as Clinton supporter Geraldine Ferraro suggested Obama's race was the reason for his stunning rise through US politics.
The Illinois senator's camp demanded she be ousted from the campaign, while Clinton said she regretted the remarks but did not cut Ferraro, the 1984 Democratic vice presidential nominee, loose.