Sen. Barack Obama scored a decisive victory in North Carolina's Democratic presidential primary Tuesday, moving him ever closer to locking up an insurmountable lead among pledged delegates, while Sen. Hillary Rodham Clinton was holding a narrow lead in the hotly contested Indiana primary as she sought to keep her shaky candidacy for the nomination alive.

A big Obama victory in North Carolina and a tight outcome in Indiana meant the senator from Illinois was almost certain to add to both his pledged-delegate margin and his lead in the popular vote. That would leave Clinton with an even more daunting challenge in finding a way to deny him the nomination.

It was a far different outcome than the Clinton campaign had hoped for. In the closing hours of the campaigns in the two states, her advisers expressed confidence that she was gaining ground on Obama in North Carolina and positioned for a clean victory in Indiana.

Obama, declaring that he is now fewer than 200 delegates away from locking up the nomination, used his victory speech in Raleigh to begin to try to heal the divisions in the party that have resulted from the long and difficult campaign and to sound the themes of a general-election race against Sen. John McCain, the presumptive Republican nominee.

"This fall, we intend to march forward as one Democratic Party, united by a common vision for this country," he said. "Because we all agree that at this defining moment in history -- a moment when we're facing two wars, an economy in turmoil, a planet in peril, a dream that feels like it's slipping away for too many Americans -- we can't afford to give John McCain the chance to serve out George Bush's third term. We need change in America."

Slow counting in Lake County, Ind., where the city of Gary, an Obama stronghold, is located, kept the Indiana race in doubt well into the night, dashing the hopes of the Clinton camp for an early projection from the networks and a prime-time victory celebration in Indianapolis.

She appeared more than a hour after Obama spoke, before any final call on Indiana had been made, to declare that she will continue fighting. "Tonight we've come from behind," she said. "We've broken the tie, and thanks to you it's full speed -- on to the White House."

But there were other signals that she and her advisers recognize the long odds she faces. Her speech was tinged with a sense of urgency, as she pleaded with her supporters to go immediately to her Web site and make a contribution to allow her to continue to campaign against a rival who enjoys a sizable financial advantage.

And, like Obama, she pledged to help unify the party, regardless of the outcome. "No matter what happens I will work for the Democratic nominee, because we must win in November," she said.

The results came after the most difficult month of the campaign for Obama. Clinton had gained momentum by winning Pennsylvania two weeks ago, and Obama's position appeared even more perilous when his former pastor, the Rev. Jeremiah A. Wright Jr., went on a public relations tour and repeated many of his most controversial statements. Obama finally made an emphatic break with Wright a week before the primaries in Indiana and North Carolina.

Roughly a third of the voters in both states said the Wright situation was very important in their vote, and those voters went heavily for Clinton. But an almost equal percentage said Wright made no difference, and they strongly supported Obama.

The economy was the dominant issue in both states. More than six in 10 voters in each state cited that issue as the most important one facing the country -- equaling the biggest percentages of the primary season. In North Carolina, those economy-driven voters backed Obama narrowly; in Indiana, they supported Clinton.

In North Carolina, Obama brushed aside a determined effort by Clinton, whose campaign believed her populist economic message and proposal for a summer suspension of the federal gasoline tax was helping her to gain ground there on her heavily favored rival. Overwhelming support from African American voters, who made up a third of the electorate, helped seal the Obama victory.

In Indiana, Clinton rode to victory with strong support from white voters, particularly working-class whites who had become the focus of both candidates. Obama enjoyed an advantage in northwestern Indiana because of its proximity to his home in Chicago, but Clinton more than made up for that with solid support in more culturally conservative southern Indiana.

The results in Indiana and North Carolina followed the pattern of previous Obama-Clinton contests. Clinton carried the votes of women in both states, while Obama won men in North Carolina and split them with Clinton in Indiana. Obama won younger voters, while Clinton carried the backing of older voters. Clinton won whites; Obama won blacks.

At stake Tuesday were 187 pledged delegates -- 115 in North Carolina and 72 in Indiana. That made Tuesday the third-biggest day of the long nomination battle in terms of delegates, but more important, it was the last big day on the calendar.

An additional 217 pledged delegates remain to be chosen in the final six contests between now and June 3: primaries in West Virginia, Kentucky, Oregon, Puerto Rico, Montana and South Dakota.

Obama entered the day with 1,745 delegates to Clinton's 1,608, according to an Associated Press tally. Included in that count are superdelegates -- elected officials and party leaders who are automatically granted a vote at the Democratic National Convention in Denver. Among those superdelegates, Clinton leads Obama 270 to 255.

The senator from Illinois has gradually narrowed what was a much larger gap in the superdelegate competition. About 270 superdelegates remain uncommitted, by most media counts.

Those superdelegates are critical because neither Obama nor Clinton can reach the 2,025 delegates needed to secure the nomination in the remaining contests. Because pledged delegates are allocated proportionally on the basis of primary results in each state, it is virtually certain that Obama will end the primaries with a lead among pledged delegates, but still short of the majority needed.

Clinton's campaign Tuesday once again raised the question of what should happen to the 366 delegates from Florida and Michigan. Both states have been barred from taking their seats at the convention because they violated party rules in establishing the dates of their primaries. Clinton's camp wants both delegations seated and has noted that, if that happens, a total of 2,209 delegates would be needed to win the nomination.

The Democratic National Committee's Rules and Bylaws Committee will meet May 31 to hear challenges on both Michigan and Florida and will make recommendations to the party about a possible resolution. DNC Chairman Howard Dean has said his goal is to seat both delegations, but he has given no ground about not allowing their delegates to play a major role in determining the outcome of the nominating contest.

Eventually the issue may go to the DNC's Credentials Committee, which takes over responsibility for determining the fate of the disputed delegations at the end of June.

Clinton herself raised Michigan and Florida during a visit to the Indianapolis Motor Speedway Tuesday morning. Asked if 2,025 or 2,209 was the real number of delegates the Democratic nominee would need to win to get the nomination, she said, "I think it's 2,209," and repeated her view that the results of primaries in Michigan and Florida should be honored.

Clinton appeared at the speedway with Sarah Fisher, one of the top women in the sport. "I'm here to see Sarah, who is a trailblazer," Clinton said as two women stood side by side in front of open-wheel race car that had been specially painted blue and had Clinton's name on it. Asked about why she was at the speedway, she said, "There's a good racing analogy, if you want to go forward, put it on D, if you want to go backwards, put it in R." Fisher then added: "Just so you know, we don't have reverse on this car."

Obama began his day in Indiana as well and later flew to North Carolina to await the results of the primaries in both states. Early Tuesday at a diner in Greenwood, Ind., Obama took a seat at the counter, ordered a ham-and-feta-cheese omelet and hash browns, and struck up a conversation with Rick Jones, a custom-home builder seated on the stool next to him.

"I've eaten breakfast every morning here for 20 years in this seat. I walk up this morning I had no idea what was going on," said Jones, who added he had nearly finished reading Obama's first book, "Dreams From My Father." Asked whom he planned to vote for, Jones said, "The person sitting next to me."

Over the final days of the campaign, Obama's events grew smaller and more casual, a mix of community picnics, diner visits and even a roller-skating party. He stopped by construction sites at dawn and factory gates at midnight.

Obama's family joined him over the weekend, which appeared to lighten his mood. But the joint pummeling from Clinton and McCain was wearing on him, his advisers said. He was struggling to promote his own cause while spending half of every speech drawing contrasts with his two opponents.

Amid the din, Obama struggled to get his message out. On Saturday morning in Indianapolis, he delivered an economic speech that had been days in the making, in which he described the rocky times that many Americans are facing as an affront to the American dream. It was an effort to break through with working-class voters, but it was overshadowed by the gas-tax rhetoric tucked in the middle of the address.

"This economy doesn't just jeopardize our financial well-being, it offends the most basic values that have made this country what it is: the idea that America is the place where you can make it if you try. That no matter how much money you start with or where you come from or who your parents are, opportunity is yours if you're willing to reach for it and work for it," Obama said.

Her campaign in Indiana, as Clinton repeated over and over again, was about "jobs, jobs, and jobs." But it was really about a restoration. As she campaigned in the Hoosier State, her rhetoric increasingly became about the economic growth during her husband's administration. At every stop, she began reciting the millions of jobs, the reduction of the deficit and the number of Americans lifted out of poverty under President Bill Clinton.

Aides said the biggest advantage in her campaign was not the Rev. Wright situation or even her momentum from the Pennsylvania primary but rather that fact that high gasoline prices and the mortgage crisis had put economic issues front and center.

Even before Pennsylvania voted, Clinton aides had targeted Indiana as a must-win. In the two months between primaries in Texas and Ohio and the vote in the Hoosier State, Hillary and Bill Clinton and their daughter, Chelsea, held more than 100 events in the state, far more than Obama and his wife.

On the advice of Sen. Evan Bayh, D-Ind., and organizers on the ground, Clinton conceded nothing to Obama, repeatedly visiting Obama's stronghold in northwest Indiana, which is part of the Chicago television market. While only campaigning in Gary a handful of times, Clinton held a huge rally in East Chicago, one of the few cities in the state with a large Hispanic population.