May 7 (Bloomberg) -- Barack Obama moved closer to clinching the Democratic presidential nomination by decisively defeating Hillary Clinton in North Carolina and losing to her by a narrow margin in Indiana.

Voters turned out in record numbers, handing Obama a 15 percentage point victory in North Carolina, the biggest and most delegate-rich in the final round of primaries ending June 3. Clinton won by 2 percentage points in Indiana.

``Once Obama won big tonight in North Carolina, he stopped her momentum train and picked up some serious steam of his own,'' Jenny Backus, an unaligned Democratic strategist, said after the vote. He ``rallied and turned the corner.''

Clinton, vowing to continue the fight for the nomination, isn't likely to make a dent in Obama's delegate lead in the five remaining states, plus Puerto Rico, still to hold contests with a total of 217 pledged delegates at stake. In addition, there are about 260 superdelegates, party officials and officeholders, who haven't declared their support.

``I'm staying in this race until there's a nominee,'' Clinton told supporters today in Shepherdstown, West Virginia.

Obama needs 183 delegates to reach the 2,025 required to claim the nomination, based on an unofficial Associated Press count of pledged delegates and an analysis of superdelegate endorsements. Clinton would need 337. Those figures don't include Florida and Michigan, which were stripped of their delegations by the Democratic National Committee for holding early primaries.

Seeking Superdelegates

While Clinton could block Obama from sealing the nomination with pledged delegates by staying in the race, a rush of superdelegate endorsements could end the contest. He already has momentum: Since the March 4 primaries in Texas and Ohio, which Clinton won, Obama has gained the support of 51 superdelegates to 23 for Clinton.

``I think we will see, with these outstanding results, a very logical increase in the number of superdelegates who support Barack,'' Obama campaign co-chairman Eric Holder said ``It is finally time to unite this party and get ready for the general election.''

Back in early February, the Illinois senator's advisers made projections for the rest of the race. The calculations have been correct for 19 of 21 contests, missing only Indiana, which the campaign expected to win by a narrow margin, and Maine where Obama scored an upset win. It also forecast the nomination would come down to the superdelegates and a decision on Florida and Michigan.

Florida, Michigan

Phil Singer, Clinton's spokesman, said the campaign will fight to seat the Florida and Michigan delegations at the party convention in August. Still, that would leave Clinton about 100 pledged delegates short of Obama's total, he said.

Clinton, 60, a New York senator, is trying to sway superdelegates with the argument that she is the better candidate to take on presumptive Republican nominee John McCain.

McCain, who sewed up the Republican nomination in March, also posted victories in Indiana and North Carolina yesterday. Still, more than 20 percent of voters in each state opted for someone else in the Republican primaries, raising the prospect of support for a third party candidate in November.

Obama, 46, speaking to supporters in Raleigh, North Carolina, last night, promised to unify the party.

Pledge of Unity

``Yes, there have been bruised feelings on both sides; yes, each side desperately wants their candidate to win,'' he said. ``We intend to march forward as one Democratic Party.''

He won North Carolina by more than 232,000 votes, topping the 214,000-vote edge Clinton took out of the April 22 Pennsylvania primary. The state is one that Obama's campaign says he could make competitive in the general election.

North Carolina, the 10th most populous state, has voted for the Republican candidate in 12 of the last 13 presidential elections. Blacks make up about 21 percent of the population and Obama drew nine out of 10 black voters in the primary.

While the state ranks 39th in median household income, growth in high-tech industries in its so-called research triangle has increased the proportion of college-educated, upper-income voters, another constituency that has favored Obama.

Clinton wasn't showing any sign of giving up. ``Thanks to you, it's full speed onto the White House,'' she told supporters in Indianapolis, while the votes were still being tallied in Indiana. ``Tonight, Hoosiers have said that you do want a president who stands strong for you.''

Washington Fundraiser

Clinton will attend a fundraiser today in Washington and hold rallies today and tomorrow in three states with primaries in coming weeks. West Virginia's primary is May 13 followed by Kentucky and Oregon the next week. Puerto Rico holds its contest June 1 and the voting ends in Montana and South Dakota on June 3.

Obama, who would be the nation's first black president, benefited from a racial divide in both Indiana and North Carolina. He won 92 percent of black voters in Indiana and 91 percent in North Carolina, where they represented a third of those casting ballots, according to exit polls cited by television networks.

Clinton, the former first lady, captured majorities among her traditional constituencies in Indiana, drawing the support of 58 percent of white men, 71 percent of senior citizens and 51 percent of lower-income workers, exit polls cited by Fox News showed.

To contact the reporters on this story: Kristin Jensen in Washington at kjensen@bloomberg.net; Catherine Dodge in Washington at cdodge1@bloomberg.net

Last Updated: May 7, 2008 13:31 EDT