READING, Pa. -- Senator Barack Obama sharpened his tone against Senator Hillary Rodham Clinton on Sunday as the six-week Pennsylvania primary contest raced to a close, with the rivals marshaling extensive resources in a battle for undecided voters and delegates that could determine whether the Democratic nominating fight carries on. In television commercials and in appearances before crowded rallies, Obama cast his opponent in one of the most negative lights of the entire 16-month campaign, calling her a compromised Washington insider. Clinton responded by suggesting that Obamas message of hope had given way to old-style politics and asked Democrats to take a harder look at him.
