(Updates with Clinton quotes, reaction) WASHINGTON With 87% of precincts reporting, Clinton won the Keystone State by 55%-45%, according to the Associated Press. The margin is large enough for Clinton to stave off calls for her to abandon her run for the White House, but small enough for Obama to declare a draw and maintain frontrunner status. The Illinois 'Some people counted me out and said to drop out,' Clinton told supporters in Philadelphia Clinton's case for the Democratic nomination rests on momentum, wins in big states and perceived electability. 'The tide is turning,' she told a roaring throng of supporters. 'It's a victory she absolutely had to have, but I don't think it changes the calculus of the race,' said Brian Gardner Heading into Tuesday's primary, Obama led Clinton in the delegate count by 1, 648.5 to 1,509.5, according to the Associated Press. A candidate needs 2,025 delegates to secure the nomination, a level Clinton is unlikely to reach without massive support from superdelegates, who are party leaders and elected officials. Obama said his campaign defied predictions of a blowout in Pennsylvania Clinton, in her victory speech, vowed to fight on for people fighting to pay their mortgages and health care bills and cope with soaring gasoline prices. But Guian McKee, a professor at the University of Virginia's Miller Center of Public Affairs, said the recent focus on cultural issues in the Democratic race has prevented both candidates, particularly Obama, from providing more details on their plans to combat the housing crisis and broader economic slump. Stuart Hoffman Obama is calling for a $30 billion Clinton has called for a $30 billion Pennsylvanians said the economy was the most important issue, but the race in recent weeks focused less on substantive policy issues than on perceived gaffes and misstatements by both candidates. Obama's remarks suggesting that working-class voters frustrated with the government cling to guns and religion prompted critics to call him elitist. Clinton's admission that a 1996 flight into Bosnia Both issues occupied the media and gave the candidates an opportunity to ramp up their attacks. Last week's debate was spikier than usual, with Obama fending off questions about his lack of a U.S. flag lapel pin and his controversial pastor, Rev. Jeremiah Wright Those issues are certain to reemerge in the general election if Obama is the nominee, a prospect the Clinton campaign has used against the Illinois The candidates accused each other of going negative. 'It's easy to get caught up in the distractions and the silliness and the tit for tat that consumes our politics, the bickering that none of us are entirely immune to and that trivializes the profound issues - two wars, an economy in recession, a planet in peril, issues that confront our nation,' Obama said in Evansville. To bolster her case with superdelegates, Clinton badly needed Tuesday's victory. Another victory in Indiana Gardner said trade, largely off the radar screen in Pennsylvania Crucially, Clinton held on to the support of working-class, white voters in Pennsylvania Most polls had shown Clinton ahead of Obama in the Keystone state by five to 10 points. Heavy media spending by Obama's better-financed campaign helped him whittle down Clinton's once-commanding lead in the state, and the candidates' finances will be an issue heading into Indiana 'We can only keep winning if we can only keep competing with an opponent who outspends us so massively,' Clinton said in Philadelphia -By Henry J. Pulizzi