Clinton is scheduled to meet with superdelegates Wednesday where she may face increased calls from within the party to step out of the race.
Obama Trounces Clinton in N.C.
Obama overwhelmingly won the North Carolina primary 56 percent to Clinton's 42 percent, thanks in part to his support among new voters and African Americans. In his victory speech he suggested the Democratic battle was nearing an end.
"This has been one of the longest, most closely fought contests in history," Obama said at a victory rally in Raleigh, N.C. Tuesday night. "And that's partly because we have such a formidable opponent in Senator Hillary Clinton."
In an apparent answer to Clinton's criticism that he is ill-prepared to withstand Republican attacks, Obama said: "The question, then, is not what kind of campaign they'll run, it's what kind of campaign we will run... I didn't get into race thinking that I could avoid this kind of politics, but I am running for President because this is the time to end it."
In recent weeks Clinton has argued Obama's failure to reach white, blue-collar workers could be a detriment in the general election fight against presumptive Republican nominee John McCain. However Clinton failed Tuesday to decisively win the Hoosier State -- despite it's wealth of the rural, blue-collar, low education voters that have typically supported her.
With former President Bill Clinton standing behind her unsmiling, Clinton offerd a more subdued tone than in past victory speeches.
"I will never give up on you, and your families, and your dreams, and your future," she said, pledging to work hard to win upcoming primaries in Kentucky, Oregon, and West Virginia, after urging supporters to go to her website and donate much-needed money to her campaign.
However Clinton then suggested that even if she were not the nominee, the Democrat on the ticket would be best for the White House.
"I want the people in these upcoming states to know we're going to work hard to reach out to all of you. Because we want you to know the Democratic party is your party and a Democratic president would be best for you," Clinton said.
Black Voters Surge For Obama in N.C.
Support from 91 percent of African-Americans voters in N.C. -- who accounted for a third of voters in the state -- lifted Obama to easy victory, according to preliminary exit poll results.
The Illinois senator also benefited from a surge of new voters who favored Obama by a heavy margin.
Battling to the end, the exhausted rivals urged North Carolina and Indiana voters to the polls Tuesday, each hoping to shake up a Democratic race that has gone on longer than anyone expected.
Highlighting her working-class message, Clinton visited the Indy 500 racetrack in Indianapolis with Sarah Fisher, a female race car driver who has endorsed her.
Asked earlier Tuesday if she would drop out of the race if she lost tonight, Clinton refused to say.
"Politics is unpredictable. So I'm just going to wait and see what the voters have to say," she said.
Clinton Had Counted on Blue-Collar Voters in Ind.
After five months of bruising primary battles, Clinton had appeared to find a groove in recent weeks, adopting a populist message, defiantly refusing to withdraw from the race, and pushing the party to seat delegates from Florida and Michigan.
She aggressively targeted blue collar and low-income voters, hammering her message that she will fight for them.
"You notice as she campaigns that she drops the ending of words, and becomes 'we're working people,'" said Peri Arnold, a professor of political science at the University of Notre Dame in South Bend, Ind. "She becomes sort of Rosie-on-the-night-shift and stylistically she becomes very attractive to these voters."
Obama has typically fared better among younger voters, people with higher-education, self-described liberals, and African Americans.
Obama, who went from living on food stamps as a child to becoming the first black president of the Harvard Law Review, has at times appeared uncomfortable in recent weeks trying to appeal to white, rural, working class voters by drinking beer and campaigning at construction sites and on factory floors.
"I think a lot of voters don't know what box to put this guy in," said Arnold, who focuses on presidential politics, arguing Obama's "cosmopolitanism" has confused voters.
"There are questions about Obama in many voters' minds about who he really is in terms of his style and his values and that's problematic because, after all, presidential politics is about connecting with the voters and giving voters a sense that they're like them in some way," he said.
Clinton, herself an Ivy League-educated millionaire and longtime Washington insider, has continued to paint Obama as an out-of-touch elitist and a flawed general election candidate. She has repeatedly argued that only she can withstand Republican attacks in the fall and right the wrongs of seven years of the Bush administration.
Despite her criticisms, a New York Times/CBS poll released Monday found Obama leads Clinton in support nationally, with 50 percent support for Obama to her 38 percent.
Bill Clinton Barnstorms Backwater Counties
Despite the negative tone of the campaign, the ongoing Democratic battle continues to energize voters and bring substantial turnout at the polls.
Obama's win in North Carolina comes despite the efforts of former President Bill Clinton, who campaigned persistently in the state over the last three weeks.
" Bill Clinton has been campaigning here pretty persistently for the last three weeks," said Steve Ford, editorial page editor of the Raleigh News & Observer.
Candidates Sparred Over Gas Tax
In the two weeks since the Pennsylvania primary, Obama and Clinton have sparred over her proposed suspension of the 18-cents-a-gallon federal tax on gasoline for the summer travel season, with the estimated $8 million in lost revenue to be made up through a new tax on oil companies.
Several economists have derided her plan, and Obama called the proposal a gimmick designed to pander to low-income voters.
Meanwhile, last week Obama disavowed his pastor of 20 years, Rev. Jeremiah Wright, who in a series of public appearances reiterated some of his most controversial statements, including that the United States had created the virus that caused AIDS, that American foreign policies invited the 9/11 attacks, and other incendiary comments.
Preliminary exit poll results indicate that just under half of Democratic primary voters in Indiana and North Carolina alike call the controversy surrounding the Rev. Jeremiah Wright an important factor in their vote.
In both states around three-quarters of voters or more say they made up their minds before last week, according to preliminary exit polls, when the controversy over Wright's comments reignited.
In recent days Clinton has tried to re-set the bar for winning the Democratic nomination. Asked what she sees the finish line of the race as, she said for the first time: "I think it's 2209."
That figure 2209 delegates assumes that Florida and Michigan's delegates are included in the overall count. However, Democratic Party officials have long said the magic number for winning the nomination was 2025, a number that does not include Florida and Michigan, states that did not hold candidate-supported primaries after a bitter dispute with the national party over the primary calendar.
"There are going to be the rest of these contests which are very significant and then in June if we haven't done it already were going to have to resolve Florida and Michigan. And they were legitimate elections," Clinton said Tuesday.
'Go to the Bitter End'
Clinton Communications Director Howard Wolfson confirmed Clinton will meet with undecided superdelegates Wednesday to "ask for their support."
While voters continue to appear energized, many in the Democratic party worry the ongoing nomination battle will hurt the party going into the general election.
"We're beyond the point of this being good for the party," Carrick said. "We're getting to the point where it's just snarky, back-and-forth, gotcha stuff that's doing damage to the party."
Preliminary exit poll results indicate a continued criticism of Clinton for the tone of the campaign. In North Carolina two-thirds of voters said she attacked her opponent unfairly, as did about six in 10 in Indiana, reports ABC News' Gary Langer. Fewer in both states -- closer to four in 10 -- said Obama attacked unfairly.
Before the primaries in North Carolina and Indiana, both candidates suggested the Democratic battle could go until the last primaries in Montana and South Dakota on June 3, and even until the party convention in Denver this August, where superdelegates could ultimately decide the Democratic nominee.
"These two candidates are prepared to go to the bitter end," predicted Donna Brazile, who ran Al Gore's 2000 presidential campaign and is an ABC News contributor.
"They're committed. They have staff, they have offices, they have telephones, they have volunteers signed up," she said. "Some of them have already visited Oregon and Montana, so let's assume it's going until the bitter end."
However after her disappointing finishes Tuesday night, and with Clinton almost out of political manouvres, her quest to become the nation's first woman president appears increasingly unlikely.
ABC News' Gary Langer, Kate Snow, Eloise Harper, and Sunlen Miller contributed to this report.
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