Barack Obama Tuesday surged to victory in Mississippi's Democratic primary, in a new triumph over Hillary Clinton, as a fierce new race row rocked their bitter White House race.

The Illinois senator punched back with his second win in a row since the former first lady pulled her campaign back from the brink of extinction, with huge victories in Texas and Ohio last week.

As Mississippi voted, the tone of the race took another nasty lurch, as the Obama camp demanded the dismissal of Clinton's supporter Geraldine Ferraro, for saying: "If Obama was a white man, he would not be in this position."

With its 33 nominating delegates up for grabs, conservative Mississippi, reliably Republican in general elections, was the last showdown in the Democratic race before the huge Pennsylvania primary on April 22.

Television exit polls handed Obama the victory within minutes of polls closing in the state, and showed a large racial divide: MSNBC figures showed nine in ten African Americans going for the 46-year-old.

Fox News exit polls said white men went for Clinton 69 to 30 percent, and white women by 74 percent to 26 percent.

Obama's victory was likely to erase the net gain of nominating delegates by the former first lady with her victories last week, leaving her still trailing by a significant margin.

The first African-American with a viable shot at the White House, Obama called the remarks in a California newspaper by Ferraro, who blazed her own historic trail by becoming the Democrats' 1984 vice presidential nominee "patently absurd."

"I don't think that Geraldine Ferraro's comments have any place in our politics or the Democratic Party," he told Pennsylvania newspaper The Morning Call.

His campaign clamored for Ferraro's head, noting the swift resignation of an Obama aide last week after her remark that Clinton was a "monster" sparked howls of outrage from the New York senator's team.

Obama's top strategist David Axelrod said the comments were part of an "insidious pattern that needs to be addressed," bringing up previous racially tinged rows between the two camps.

But Clinton said only that she did "not agree" with Ferraro's portrayal of Obama as the privileged recipient of affirmative action, and found it "regrettable" that supporters might resort to personal attacks."We ought to keep this focused on the issues.

That's what this campaign should be about," she said while stumping in Pennsylvania ahead of the state's crunch primary.

Later on Fox News, Ferraro refused to apologize, accused the Obama campaign of waging a hate campaign against her, and reiterated that the candidate's political success was "in large measure because he is black."

"I said this (Obama's) is one of the best campaigns. I speak about his star quality. I talk about how exciting it is to have two campaigns, but you know, the truth is the truth is the truth," Ferraro added.

Clinton's campaign manager Maggie Williams accused the Obama team of waging "false, personal and politically calculated attacks on the eve of a primary."

Heading into Tuesday's primary, Obama had 1,589 nominating 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.

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 percent 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.

On 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.

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.