Obama Holds Delegate Lead
An MSNBC count showed Clinton sliced Obama's national delegate lead by nine in Pennsylvania. Obama now has 1,726 delegates to Clinton's 1,593, short of the 2,024 needed to clinch the nomination.
Neither candidate can win without help from superdelegates -- nearly 800 party insiders who are free to support either Obama or Clinton. Obama campaign manager David Plouffe said he expected those superdelegates to move toward the winner and end the nomination fight sometime after June 3.
"You're going to see the superdelegates make a decision shortly after that," he said.
Clinton hopes a strong run through the last contests brings her closer in delegates won and votes cast and convinces those superdelegates she is the Democrat who can beat McCain.
Both candidates picked up new superdelegate support on Wednesday, with US Rep. John Tanner of Tennessee backing Clinton and Oklahoma Gov. Brad Henry supporting Obama.
Democrats have become increasingly worried about the negative tone of the race, and exit polls showed Pennsylvania voters shared the concern.
About two-thirds of Pennsylvania voters thought Clinton unfairly attacked Obama, while about half thought Obama had unfairly attacked Clinton, the polls showed.
But Clinton won 58 percent of those who decided in the last week, when Obama was on the defensive in a debate over a series of campaign controversies and Clinton questioned his toughness in an ad featuring images of al Qaeda leader Osama bin Laden.
"I know that people like to talk tough and use a lot of rhetoric about fighting and obliterating and all that stuff," Obama said. "I've always believed that if you're tough you don't have to talk about it."
The North Carolina Republican Party launched an ad in the state criticizing Obama and his controversial former pastor, the Rev. Jeremiah Wright, who has come under fire for inflammatory views including saying the US government spread the AIDS virus to blacks.
McCain asked the state party to withdraw the ad, which also criticized Democratic North Carolina candidates for governor Beverly Perdue and Richard Moore for their endorsements of Obama and called him "too extreme for North Carolina."
Obama and Clinton both campaigned in Indiana on Wednesday before heading back to Washington for a Senate vote.