Sen. Hillary Rodham Clinton won Pennsylvania's Democratic primary today, keeping her presidential candidacy alive to the next round against Sen. Barack Obama. Voters swarmed the polls in high numbers, given the chance to have a meaningful say in a presidential nomination for the first time since 1976. Clinton scored her victory by winning the majority of the votes of blue-collar workers, women and white men in an election in which the economy was the dominant concern, according to exit polls. Blacks, more affluent Democrats, and voters who recently registered Democratic sided with Obama, the exit polls showed. With no other contests on the schedule, the candidates hop-scotched across Pennsylvania for nearly seven weeks, spending $20 million on TV advertising - a bombardment that, for example, featured 228 spots a day in the Harrisburg media market. Obama, his campaign flush with cash, was able to outspend Clinton by a ratio of about 3-1 on the air. In its final days, the campaign turned sharply negative. Obama accused Clinton of practicing 'slash-and-burn' politics, divisiveness and of being a captive of special interests. She ran a TV ad that featured images of Osama bin Laden, the bombing of Pearl Harbor and Hurricane Katrina and suggested Obama could not handle the pressures of the Oval Office. 'Who do you think has what it takes?' asked the ad, the first one in which a Democrat used bin Laden against a fellow Democrat. For Clinton the stakes were especially high Win, or go home. Even with the Pennsylvania win, she trails Obama by a significant margin in the delegate count, and her campaign's best hope was that a big victory here would buttress her case to Democratic superdelegates that Obama is less electable against Republican John McCain this fall. Obama has struggled in some states to win over white working-class voters, older voters and Catholics, key parts of the coalition that strategists say a Democrat needs to carry big industrial swing states. 'A win is a win, especially under the circumstances where my opponent has outspent me probably 3-1, maybe 4-1,' Clinton said after a visit to a polling station today at Friendship House in Conshohocken. A loss by Obama would continue to raise electability questions, she said. 'Why can't he close the deal?' Clinton asked. 'With his extraordinary financial advantage, why can't he win a state like this?' For his part, Obama said that anything less than a blowout win here for Clinton would do little to help her overcome his delegate lead because delegates are awarded proportionally. 'Going into this six weeks ago, the Clinton campaign suggested that they were unbeatable' in Pennsylvania, Obama said. Polls showed that Clinton always had the advantage among women, older voters, Catholics, union households, and white voters with high school educations making less than $35,000. Obama was leading among younger voters, African Americans, Democrats with incomes over $75,000, and liberals. The state seemed demographically tailor-made for Clinton, with higher percentages than the nation as a whole of voter groups that have favored her in past races. Obama was counting on Philadelphia and its suburbs to overcome expected Clinton support in the west, central and northeastern Pennsylvania. They said Obama was leading in Philadelphia and its suburbs, while Clinton led in western and northeastern Pennsylvania. Clinton's campaign was on the verge of elimination after 11 losses last month before she won popular-vote victories in Ohio and Texas based on her advantage with the working class. Obama whittled away at Clinton's once-formidable lead in Pennsylvania polls but then hit a rocky patch that analysts said halted his momentum. There was the disclosure of remarks he made at a fund-raiser, characterizing small-town Pennsylvanians as 'bitter' people who cling to guns religion and 'fear of people not like them' because of their economic frustrations. Many viewed the remarks as insulting, and Clinton stoked that response. In a televised debate last week, Obama was thrown on the defensive about everything from inflammatory comments by his former pastor to his friendship with a member of the radical Weather Underground, to why he rarely wears an American flag pin in his lapel. Obama had appeared to weather the storm over the pastor, the Rev. Jeremiah Wright, giving a well-received Philadelphia speech on race relations in which he condemned Wright's incendiary sermons. For her part, Clinton was caught mischaracterizing her landing under sniper fire in Bosnia on a 1996 visit, a story she was using to establish her foreign-policy bona fides. The sniper incident and 'bittergate' might be examples of the candidates showing the wear and tear from the extended campaign. Clinton began the campaign with doubts about her trustworthiness, but her negative ratings have risen sharply in the last few months. And Obama's troubles convinced the GOP that he could be vulnerable in the fall, should he become the nominee. At stake in Pennsylvania were 158 delegates to the Denver convention, the largest prize left. Clinton was preparing to celebrate the victory with a party at the Hyatt Bellevue, while Obama had left the state. He was in Evansville, Ind. as the returns came in, getting a jump on an important May 6 primary state at a rally with rock star John Cougar Mellencamp.