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PAOLI, Pennsylvania (Reuters) - Democratic presidential candidate Barack Obama accused rival Hillary Clinton on Saturday of shifting positions and waging a negative campaign as the two candidates sped across Pennsylvania before next week’s potentially make-or-break primary election.

Obama, an Illinois senator who is the party’s national front-runner but behind in Pennsylvania, hopes an upset will hand him the Democratic nomination and knock Clinton, a New York senator, out of the race to compete against Republican John McCain in the November general election.

He said the former first lady had adopted an attitude of, “We’re going to throw whatever we want at Barack, whether it’s true, whether it’s false, whether it’s exaggerated, whether it’s relevant, because that’s, according to Senator Clinton, what the Republicans will do.”

“What’s happened is that Senator Clinton has internalized a lot of the strategies, the tactics that have made Washington such a miserable place where all we do is bicker and all we do is fight,” he told a rally in Paoli, Pennsylvania, a suburb of Philadelphia.

His comments came after a contentious television debate on Wednesday that focused largely on issues such as his controversial former pastor, his recent relationship with a 1960s radical, his remarks about small-town voters and his failure to wear a flag lapel pin.

Clinton has seen her sizable advantage over Obama in Pennsylvania dwindle to a single-digit lead, but a Gallup daily tracking poll released on Saturday gave her a slight edge among Democrats nationwide -- putting her ahead of her rival in that ranking for the first time since mid-March.

Clinton, who said Obama could not stand the pressure of the nation’s top job after he complained about the questions in Wednesday’s debate, alluded to the same theme on Saturday.

“When you get into the general election and when you get into the White House, the stresses and pressures of the general election and the job are overwhelming,” she told a rally in West Chester, another Philadelphia suburb.

Clinton campaign advisers sought to play down expectations of a big victory once polls close at 8 p.m. (0000 GMT) on Tuesday. They highlighted Obama’s financial advantage and advertising blitz.