WASHINGTON — After a six-week hiatus, the Democratic presidential contest goes back to the voters Tuesday, when Pennsylvania holds a primary that is a make-or-break contest for Hillary Rodham Clinton's struggling campaign.
It also is a test of whether Barack Obama can regain his momentum despite recent controversies and can win over blue-collar voters who have been cool to him elsewhere.
The candidates spent the weekend crisscrossing the Keystone State in the final days before balloting, the first Democratic primary since Mississippi's on March 11.
Obama, in what he called his "closing argument" Sunday in Reading, described Clinton as disingenuous for revising positions to suit voters' tastes.
"Her basic view about this election is that the 'say anything, do anything' special-interest-driven politics in Washington is how it's got to be," he said. "That's how the game is played. And so you should elect her to be the nominee because she has been in Washington longer and she knows how to play the game better."
Clinton hopscotched the state, countering that it was Obama, not she, who had been clouding these last days of campaigning with negativity and misleading statements.
"I was raised by my family to say what I mean and mean what I say," she told a crowd in Bethlehem on Sunday.
The last few weeks of campaigning have not been kind to either candidate: Clinton's once-commanding lead in Pennsylvania polls has dwindled, while Obama has come under fire for his former pastor's incendiary remarks, his association with a Vietnam-era radical and a comment that some thought demeaned "bitter" rural voters.
The stakes in Pennsylvania are high as the candidates head into the stretch drive of a race being run on two levels.
On one level, they are still fighting to collect more committed delegates to the nominating convention, although it is hard to see, mathematically, how Clinton can overcome Obama's advantage.
But because neither can sew up enough elected delegates to cinch the nomination, they are also campaigning for the hearts and minds of superdelegates -- the party activists and officials who can back either candidate and will probably decide the contest.
The support of 2,024 convention delegates is needed to clinch the nomination. According to a weekend count by the Associated Press, Obama has 1,645, compared with Clinton's 1,507, though she has the backing of more superdelegates who have stated a preference. Obama is ahead in the popular vote, 13.4 million to 12.7 million.
Pennsylvania has 158 delegates up for grabs, and the state's demographic makeup plays to Clinton's strengths. But if the New York senator does not score a decisive victory, her hopes for muscling her way to the nomination could fade, if not vanish.
Obama has spent weeks in Pennsylvania and flooded it with campaign money. But if the Illinois senator proves unable to reach beyond his coalition of African American, affluent and well-educated voters, uncommitted superdelegates may question his strength as a general election candidate. Blue-collar white voters will be crucial in the campaign against John McCain, the presumptive GOP nominee.
The battle for these voters has produced jarring scenes of the candidates -- both Ivy League-educated millionaires -- scrambling to establish their credentials as friends of the working class. Obama went bowling and sharpened his focus on economic issues that are crucial to beleaguered industrial workers. Clinton knocked back a whiskey shot in a bar and reminded voters that although she grew up in a comfortable Chicago suburb, her grandfather began working at a Scranton lace mill at 11.
After the breakneck pace of the first three months of the 2008 primary season, the six-week run-up to Tuesday's vote has been the longest stretch of pure campaigning since the process began in January. Pennsylvania is the first of 10 states and territories that will have contests before Montana and South Dakota close out the Democratic voting calendar on June 3.
A recent Los Angeles Times/Bloomberg poll showed Clinton leading Obama in Pennsylvania by 5 percentage points, a decline from previous polls that had her ahead by double digits. The state has been considered hers to lose because it is packed with constituencies she has dominated -- the elderly, Catholics, blue-collar whites -- especially in rural areas and in western Pennsylvania. She has been endorsed by much of the state's Democratic establishment, including the popular governor, Edward G. Rendell, and Philadelphia Mayor Michael Nutter.
"She obviously has a home-court advantage," Rep. Chaka Fattah (D-Pa.), an Obama supporter, said Sunday on CNN's "Late Edition." But Obama has high-wattage endorsements of his own, including that of Sen. Bob Casey, an antiabortion Pennsylvania Democrat who is expected to ease conservatives' concerns over Obama's support for abortion rights.