Republicans are trying to change the focus of the U.S. presidential race between their candidate, Senator John McCain, and the Democratic nominee, Senator Barack Obama. A new wave of Republican attacks now target Senator Obama's background and raise questions as to whether he is fit to be president. VOA National correspondent Jim Malone has the latest on the presidential campaign from Washington.

Senator McCain's vice presidential running mate, Alaska Governor Sarah Palin, stepped up the attacks Monday during a campaign rally in Florida.

Palin highlighted Obama's past links with a former 1960s radical, Bill Ayers, who was part of the so-called Weather Underground that set off bombs in government buildings to protest the Vietnam War.

"His own top adviser said that they were, quote, certainly friendly," she said. "In fact, Obama held one of his first meetings of his political career in Bill Ayer's living room. I am just so fearful that this is not a man who sees America the way that you and I see America, as the greatest source for good in this world."

Ayers is now a college professor who lives in Obama's neighborhood in Chicago. Ayers served with Obama on two charity boards and hosted a reception for him in 1995.

Obama has denounced Ayer's radical past and the Obama campaign says the two men are not close.

During a campaign stop in North Carolina, Obama accused the McCain campaign of trying a new tactic in order to avoid talking about the weakened U.S. economy, which the polls suggest is the top issue for voters this year.

"His campaign has announced that they plan to, and I quote, turn the page on the discussion about our economy and spend the final weeks of this campaign launching Swiftboat-style attacks on me," he said.

The Obama campaign is also striking back at McCain. The campaign launched an Internet ad reminding voters that the Senate Ethics Committee rebuked McCain for using poor judgment because of his involvement with former banker Charles Keating, a convicted felon at the heart of the U.S. savings and loan scandal of the late 1980s.

Surrogates for both candidates are predicting a nastier tone to the campaign as it enters the final weeks.

"He has been critical not only of the president, but of American policy, and he has kind of a negative view of America in the world," said Republican Congresswoman Heather Wilson of New Mexico, who appeared on the CBS program Face the Nation.

Democratic Senator Dianne Feinstein of California says she expects more personal attacks against Obama in the weeks to come. Feinstein also spoke on Face the Nation.

"He's leading in the polls and he's leading in most of the battleground states, and this is going to be a month, I think, of character assassination," she said.

Political experts say the focus on the U.S. financial crisis has helped Obama surge past McCain in public opinion polls. They say McCain will now try to shift the election debate away from the economy to questions about Obama's character.

"What this has done is refocus the campaign on pocket book issues, and historically that kind of focus helps Democrats," said Tom DeFrank, Washington bureau chief for the New York Daily News and a guest on VOA's Issues in the News program. "And we have seen in the last ten days a significant shift away from McCain and towards Obama, and I think it is directly related to the economic fears."

Senator McCain's next best opportunity to change the focus of the campaign comes Tuesday when he and Senator Obama meet for their second presidential debate in Nashville, Tennessee.

Tuesday's debate will feature a town hall format where members of the audience will ask questions, a format that Senator McCain prefers.

Obama and McCain will take part in one last debate on October 15 at Hofstra University in New York. The election is November 4.