Bill Clinton, still popular with grass roots Democrats, said Biden and Obama were better prepared than Republican John McCain to pull America out of the financial crisis.

He called on his wife's supporters, in a state where she won a thumping 10 per cent victory over Obama in the primary season, to look into their hearts.

"You need to remember, if you supported her, why you did it," Clinton said, urging those who shared his wife's crusade for healthcare reform and advocacy of the middle class to chose Obama.

"If you ask yourselves who has the best ideas, who's got the best instinct, who's got the best ability to understand these challenges, who's got the best supporting cast, the answer is Barack Obama.

"That's why Hillary's here, that's why I'm here," Clinton said.

Biden paid tribute to both Clintons and portrayed himself and Obama as the natural inheritors of their political legacy.

"Everything she's devoted her life to has been on the side of people who have been on the other side of power," Biden said.

Most polls show Obama with a handy lead in Pennsylvania, but the McCain campaign, especially by deploying vice presidential pick Sarah Palin, is making a hard push for social conservative swing voters.

Hillary Clinton won a stunning 18 million votes in her six-month coast-to-coast nominating showdown with Obama, so she is set to play a vital role in the closing days of the election.

Republicans had hoped that simmering hostility towards Obama from her supporters, especially white blue-collar voters in swing states, could provide an opening for McCain and Palin.

The sudden depth of the financial crisis however has boosted Obama's ratings and polls show that more voters trust him to fix the economy than McCain - a factor powering the Democrat's growing advantage in battleground states.

Clinton was due to campaign for Obama in Philadelphia, Pennsyvlania today and then head to West Virginia and Arkansas, and was expected to be on the trail in a long pre-election run.

Bill Clinton was next headed to Virginia, in the past a solid Republican state which appears in danger of falling to Obama on November 4.

The former president was said to have been fuming over his wife's defeat, but went a long way toward burying the hatchet with a warm endorsement of Obama at the Denver nominating convention in August.

He said in Scranton that his wife had done more than 50 appearances on behalf of the Obama-Biden ticket in an apparent bid to defuse criticism that the Clintons have not campaigned enough for Obama.

"She has done more than all of the runner ups combined," he said.

Several Democrats at the rally said the economic malaise was a key factor in their vote.

"I came to see Joe Biden and President and Senator Clinton," said Scranton resident Joe Tully, 77, next to his wife, Anne, a former Hillary Clinton supporter.

"In a way I feel sorry for him (Obama), the things he is getting into when he gets in office," she said.

AFP