McCain, trailing in national and key state opinion polls less than a month before the Nov. 4 election, accused Obama of a "barrage of angry insults" and questioned if the Illinois senator had ever accomplished anything. "Who is the real Barack Obama?" he asked at a campaign stop in New Mexico.
"It's as if somehow the usual rules don't apply, and where other candidates have to explain themselves and their records, Senator Obama seems to think he is above all that," McCain said.
The attack followed the McCain camp's renewed criticism of Obama for serving on a community board in Chicago with former 1960s radical William Ayers. The Obama campaign fired back with a Web advertisement and video on McCain's involvement in the Keating Five savings and loan scandal two decades ago.
"This is someone who sees America as imperfect enough to work with a former domestic terrorist who targeted his own country," McCain's running mate Sarah Palin said of Obama in Clearwater, Florida. Over the weekend she accused Obama of "palling around" with terrorists.
"McCain's Keating history is relevant and voters deserve to know the facts," Obama campaign manager David Plouffe said of Obama's new attacks over the Keating scandal. The Obama campaign on Sunday called McCain, 72, "erratic" on the economic crisis.
The increasingly angry exchanges came one day before the second debate for the presidential rivals, with McCain hoping a strong performance can give him new life in the race and slow Obama's momentum.
Concerns about the economy have helped lift Obama, as polls show voters prefer his economic leadership. Stocks tumbled on Wall Street again on Monday in a sign the $700 billion government bailout of U.S. financial institutions had not eased concerns.
McCain's advisers want to change the focus of the race from the economy back to Obama and his associations with figures like Ayers, a founder of the Weather Underground group that carried out several bombings in the 1960s.
Obama criticized McCain for wanting to "turn the page" on the economy, as one of his advisers was quoted as saying in the Washington Post over the weekend.
"I cannot imagine anything more important than to talk about than the economic crisis," Obama told reporters in Asheville, North Carolina, where he has been preparing for the debate.
'Political Shenanigans'
Obama, 47, was a child when the Weather Underground was active and has condemned the group's activities. He says he barely knows Ayers, who contributed to one of his Illinois state senate campaigns and once held a coffee for Obama at his house.
In response to the attacks, Obama's campaign released its own Web advertisement recalling McCain's participation in two meetings with banking regulators on behalf of his friend Charles Keating, who was later convicted of securities fraud.
The scandal was part of a larger crisis in the late 1980s and early 1990s—reminiscent of the current turmoil on Wall Street—when hundreds of savings and loans collapsed, costing U.S. taxpayers over $100 billion.
McCain was cited by the Senate ethics committee for "poor judgment" and McCain has repeatedly described his activities as a mistake.
The campaign's angry tone sets up a potentially heated debate on Tuesday night in Nashville, Tennessee, the second of three encounters between the presidential contenders. The last debate will be on Oct. 15 in Hempstead, New York.
"The tone of tomorrow's debate will probably be much more negative," said Republican consultant Todd Harris, a McCain aide during his failed 2000 presidential bid.
"Because McCain has already set the expectation that he is going to aggressively go after Obama, I think we can expect McCain to spend the entire night on offense," he said.
Polls judged Obama the winner of the first debate, but the Tuesday debate will be conducted with a town-hall format, the favorite format for McCain's campaign stops and a longtime strength for him.
The questions will be asked by members of a group of about 100 undecided Nashville voters identified by the Gallup polling company. The participants will meet with moderator Tom Brokaw of NBC News on Tuesday, and he will select the questioners.
The candidates will sit on stools and be free to roam the stage at Belmont University in a less structured environment.
