Clinton needs convincing win

Pennsylvania - Democrats in Pennsylvania choose between Hillary Clinton and Barack Obama in a bitterly-fought primary on 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.

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 female president.

Polls opened in the economically pummelled northeastern state at 11:00 GMT and close at 00:00 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 multimillion-dollar campaign financing race.

But her camp stresses electability, not electoral mathematics, and on Monday she vowed to fight on until the end of the voting calendar.

Remarks may have dampened poll surge

"I'm going until everybody's had a chance to vote in this process," she said in a CNN interview."

Victory here would bolster Clinton's claim that only she can solidify the Democratic powerbase, woo socially conservative working-class voters, and prevail in crucial presidential battlegrounds.

Obama has spent millions of dollars in advertising in the state, and sharpened his attacks on Clinton, in an apparent bid to land a knockout that would allow him to set his sights on Republican John McCain.

But his remarks at a San Francisco fundraiser that some small town Americans were "bitter" over the economic squeeze, and so clung to religion and guns, may have dampened his poll surge, which saw him cut Clinton's lead to a few points.

Latest opinion surveys appeared to show Clinton headed for victory, but her hopes of a campaign-altering blowout seemed uncertain.

She led Obama 52% to 42% in a Suffolk University survey. A Quinnipiac University poll had her up seven points, 51-44%.

Obama, who matched Clinton's intense sprint round the state's major media markets on Monday, however predicted in an interview with a Pittsburgh radio station that he would do surprisingly well.

"I am not predicting a win. I am predicting it is going to be close and we are going to do a lot better than people expect," he told KDKA.

Clinton is making her fervent case to Democratic "superdelegates", the party officials who will now effectively crown the nominee, since neither candidate is likely to reach the 2 025 pledged delegates needed to win outright.

- AFP