With the election four weeks away, chances dimmed that Republican John McCain and Democrat Barack Obama could reclaim the often lofty images they cultivated early in their presidential bids as their campaigns focused new attention Monday on decades-old events involving a former radical from Chicago and a convicted thrift owner from Arizona.

McCain's campaign added another figure when his running mate, Sarah Palin, said there should be more discussion of Obama's incendiary former pastor, Jeremiah Wright.

Obama and McCain faced cameras Monday with harsh words for each other. Obama, taking a break from debate prep in Asheville, N.C., accused McCain's campaign of "smear tactics."

In Albuquerque, N.M., McCain delivered an unusually scathing broadside. He accused Obama of lying about McCain's efforts to regulate the home loan industry. And he suggested Obama is a mysterious figure who cannot be trusted.

"Who is the real Barack Obama?" McCain said to a cheering crowd. "Ask such questions and all you get in response is another barrage of angry insults."

Some analysts called the change in tone disappointing but predictable. Presidential candidates who are losing on policy issues often turn to character, they said.

As McCain's poll standings fell along with the economy, his campaign began the new character criticisms and used Palin to spearhead the push. Obama's campaign didn't wait long to respond.

Brookings Institution political scientist Thomas E. Mann said he had felt for months that McCain "would eventually have to try to undermine Obama as an acceptable choice for president and commander in chief." Key issues, he said, including "an economy in turmoil, an unpopular war and a politically discredited president are working powerfully against McCain and the Republican Party in general."

Obama, meanwhile, has learned the lessons of Michael Dukakis and John Kerry. Those Democrats lost presidential elections after hesitating to counter hard-hitting and factually dubious attacks on their character and judgment. The shorthand terms for those attacks _ "Willie Horton" and "Swiftboating" _ have become a call-to-arms for Democratic activists who vow always to return fire with fire.

"We don't throw the first punch, but we'll throw the last," Obama said Monday on Tom Joyner's syndicated radio show.

Several Democrats said on Sunday talk shows that Obama's campaign would revisit McCain's long-ago involvement in the thrift scandal if the personal attacks on him continued. Within hours, the Obama campaign released a memo and Web video doing just that.

Obama and McCain have hit each other at personal levels before. But the vitriol increased dramatically Saturday, when Palin repeatedly raised Obama's relationship with former 1960s radical Bill Ayers.

Obama, she said, was "palling around with terrorists who would target their own country."

Ayers helped found the violent Weather Underground group, whose members were blamed for several bombings when Obama was 8. Obama has denounced Ayers' radical views and activities.

The two men live near each other in Chicago, and once worked on the same charity board. Ayers hosted a small, meet-the-candidate event for Obama in 1995, at the start of his political career, but multiple news accounts have said they are not close. The campaign called Palin's remarks outrageous and grossly exaggerated.

A 13-minute Web video Obama's campaign released Monday revisits McCain's ties to Charles Keating, a former friend, campaign contributor and savings and loan owner who was convicted of securities fraud in 1991.

As a senator, McCain participated in two meetings with banking regulators on Keating's behalf. He became one of the "Keating Five" senators investigated by the Senate ethics committee. The panel cited McCain for a lesser role than others, but criticized his "poor judgment."

McCain has since called his involvement with Keating "the worst mistake of my life."

McCain and Obama say they are dredging up Ayers and Keating because the episodes shed light on each other's current judgment _ and because the other campaign is on the attack, though a McCain aide said the GOP campaign wanted to change the subject from the failing economy.

A few months ago, both candidates promised something better.

Obama, extolling a new brand of politics, told an Iowa audience in January: "We can't afford the same old partisan food fight. We can't afford a politics that's all about tearing opponents down instead of lifting the country up."

McCain, shaken by a vicious whisper campaign in South Carolina that helped George W. Bush beat him there during the 2000 Republican primaries, has often vowed to be a straight-shooting candidate who puts honor ahead of winning. When Republicans attacked fellow retired Navy officer Kerry in the 2004 "Swiftboat" episode, McCain called the ads "dishonest and dishonorable."

Earlier in this campaign when the North Carolina Republican Party said Obama's relationship with Rev. Wright made him "too extreme," McCain asked it to stop and said: "There's no place for that kind of campaigning, and the American people don't want it."

The new tone may depress many, but a top independent pollster in the battleground state of Pennsylvania said it's unlikely to change many minds.

"The economy is so dominant and the change focus so great, I just don't think voters are going to buy into it," said Terry Madonna, a political scientist at Franklin and Marshall College.

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On the Net:

McCain: http://www.johnmccain.com

Obama: http://www.barackobama.com

(This version CORRECTS Corrects that losing candidates go after character; SUBS Obama quote for Rosen in 11th graf pvs, I just ....; STANDS for BC-Campaign-Character Attacks listed on AP News Digest. AP Video.)