PHILADELPHIA (AP) -- Why can't Barack Obama close the deal?
It's a question Hillary Rodham Clinton and her surrogates raised through the last days of the caustic Pennsylvania primary contest. And unfortunately for Obama -- who lost to the former first lady by a 10-point margin Tuesday night -- it's a question that bears repeating.
The loss, despite a massive cash infusion and robust campaign presence in the state, underscores the persistent problems he's had winning over many of the voters who form the traditional Democratic party base.
While the Illinois senator remains overwhelmingly popular among blacks, affluent voters and young people, other groups key to building the Democratic coalition remain elusive.
Clinton bested him among white, blue-collar voters by a margin of 69 percent to 30 percent in Pennsylvania, similar to her showing in Ohio last month. She also won older voters, women and whites and improved her margins among white, non-Catholic men.
To be sure, Obama has performed well among those groups in a handful of primaries, including Wisconsin and Virginia, both likely general election swing states.
Obama surely will emerge with sufficient delegates to maintain his overall lead, and Clinton's win in Pennsylvania will not do much to close the popular vote gap as she tries to eat into his margin. But the sense of momentum that propelled him to crushing margins across 11 contests beginning in February has slowed, raising concerns among many party activists that he will be left bruised and limping by the time the primaries end in June.
The Obama campaign points to the many advantages Clinton enjoyed in Pennsylvania: its large population of working class voters and seniors played to her strengths, and her family enjoys deep roots in Scranton, in the northeastern part of the state -- a fact the New York senator never failed to bring up on the campaign trail.
Former President Clinton, who remains a popular figure here, campaigned extensively for his wife. And she had the support of Ed Rendell, the state's popular governor and a savvy political operative in his own right.
But Obama had considerable strengths of his own -- money first and foremost. He spent $11.2 million on television ads to Clinton's $4.8 million. He spent countless more on phone banks, mail and voter targeting.
Surveys among Pennsylvanians after they left the polls showed they viewed Obama as more honest and trustworthy than Clinton, and that they favored a candidate who can bring about change -- Obama's core message -- over one who, like Clinton, has had years of political experience.
The six-week hiatus after the last major primary in Mississippi were not particularly kind to either candidate.
Obama was forced to defend his association with his pastor of 20 years, Jeremiah Wright, after videos surfaced showing Wright delivering sermons from the pulpit in which he cursed the United States as racist and denounced the government for allegedly supporting terrorism and spreading the HIV virus. Obama also was confronted with his own comments at a fundraiser in San Francisco, where he described small-town voters as bitterly clinging to guns and religion.
In the same period, Clinton came under withering criticism for her discredited tale of coming under sniper fire at an arrival ceremony in Bosnia as first lady in 1996. She stuck to the falsehood until television footage of the peaceful arrival surfaced, forcing her to acknowledge that she ''misspoke.''
Clinton also goes into the final nine contests at a significant cash disadvantage, although she said Wednesday morning in a round of television interviews that her campaign had raised $3 million online since winning Pennsylvania. She also must fight the perception that she is damaging Obama's chances in the general election by fighting on even with little chance of overcoming his lead in delegates and the popular vote.
The candidates face their next major test May 6, with primaries in Indiana and North Carolina.
Phil Trounstine, director of the Survey and Policy Research Institute at California's San Jose State University, said that Obama's problems with key Democratic demographic groups are temporary and say nothing about how he would fare with those voters in a general election.
''The notion that Obama cannot attract core constituencies is only being tested in matches against Hillary Clinton. That's not an argument that he can't win them against John McCain,'' Trounstine said. ''If Barack Obama were the nominee, you would expect Ed Rendell and (Philadelphia mayor) Michael Nutter would work like crazy to deliver Pennsylvania. The same thing would happen in California and Texas, which Clinton also won.''
After the drubbing he took in Pennsylvania, Obama needs to hope the so-called superdelegates likely charged with settling the contest will find that argument persuasive. Otherwise, what has been an epic Democratic nominating contest may be lurching toward virtual stalemate.