Democrats in Pennsylvania were choosing between Hillary Clinton and Barack Obama in a bitterly fought primary Tuesday that Clinton must not only win, but win convincingly to rescue her trailing White House bid. The New York senator is tipped for victory in late opinion polls, but many observers think it will take a double-digit triumph to stave off more calls for her to quit the epic Democratic nomination race. She also needs a fresh burst of momentum ahead of the next round of contests in Indiana and North Carolina on May 6, which are followed quickly by the last six voting showdowns of the epic nominating battle into early June. “I don't think the margin matters. I think a win is a win,” Clinton told NBC television, asked if she might drop out if unable to win by a wide margin. “We'll see what happens,” she added. “The bottom line is we have a lot of contests yet to go. This is a really close race.” A shock win by Obama would narrow Clinton's already unlikely route to the nomination, and likely snuff out her historic quest to be the first woman president. Polls opened in the economically pummeled northeastern state at 7 A.M. (1100 GMT) and close at 8 P.M. (0000 GMT). The former first lady's position is already perilous. She trails Obama in total nominating contests won, pledged delegates apportioned in those showdowns, the popular vote, and the crucial multi-million
