Is John McCain's attempt to tie Barack Obama to Britney Spears and Paris Hilton in an attack ad this week the "Swift Boating" of Obama?

The ad launched this week suggests Obama is nothing more than a lightweight celebrity akin to Spears or Hilton. A previous ad took issue with Obama's canceled visit to injured troops. McCain has suggested Obama would rather lose a war than an election and ridicules him for the "audacity of hopelessness" in his Iraq policies.

"He's the biggest celebrity in the world," his latest ad asks. "But, is he ready to lead?"

Despite the confrontational strategy -- welcomed by some Republicans -- experts on Thursday said McCain's recent barrage and charges isn't as vicious as the 2004 Swift Boat campaign against John Kerry. But the McCain effort, led by Karl Rove protégé Steve Schmidt, has the same objective: to demonize a little-known presidential candidate.

But in striking an aggressive pose, McCain is in danger of letting the caricature of an angry, petulant candidate take seed -- not so much because he is one, but because it stands in stark contrast to Obama's carefully cultivated, well, celebrity, and McCain's own promises to run a respectful campaign.

"The campaign is making him seem angrier than he is and therefore it's a disservice to him," said John Weaver, McCain's former senior strategist, who left the campaign in a shake-up last year.

Framing a portrait

Angry candidates don't win elections. Ronald Reagan and Bill Clinton won by running as sunny optimists -- one promised John Winthrop's "shining city upon a hill" and the other was the "man from Hope."

But McCain wants the presidential campaign to be about Barack Obama. To that end, McCain is helping frame a not-so-flattering portrait of Obama for voters. His ads have become increasingly tough; a third of his commercials portray Obama negatively, a new study concluded.

In working to sow doubts about Obama, McCain and his campaign have worked on a specific story line that the Democrat is not tested and not ready to lead.

Polls show that the race remains tight. State polls by Quinnipiac University show Obama leading McCain in Pennsylvania, and McCain and Obama tied in Minnesota, Ohio and Florida.

No doubt Obama has fame. He fills political venues. He breaks fundraising records. He does not have a name recognition problem. But Obama himself concedes that his challenge is getting voters to see him as president.

Obama, the first black candidate with a serious chance of winning the White House, said McCain and his Republican allies will try to scare voters by saying: "You know, he's not patriotic enough, he's got a funny name, you know, doesn't look like all those other presidents on the dollar bills."

McCain's campaign accused Obama of playing "the race card," and called the remarks "divisive, negative, shameful and wrong."

Until now, the subject of race has been almost taboo in the campaign.

"I'm disappointed that Senator Obama would say the things he's saying," McCain said in Racine, Wis. He said he agreed with his campaign manager Rick Davis' statement earlier that "Barack Obama has played the race card, and he played it from the bottom of the deck."

Obama campaign manager David Plouffe said McCain "is using the same, old low-road politics ... to distract voters from the real issues."

Nicolle Wallace, a senior McCain campaign adviser, said the ad was also about issues. She said it wasn't a low blow, mean-spirited or evidence of Rove-like campaigning but a "celebration" of Obama's celebrity and a way to force the Obama campaign to talk about issues.

Strategy has precedents

As of last week, more than 90 percent of the ads aired by Obama did not mention McCain, whereas one-third of McCain's ads referred to Obama negatively, said a study by the Advertising Project at the University of Wisconsin.

"McCain is narrative-building," said Allan Louden, an associate professor of communication at Wake Forest University, in Winston-Salem, N.C. McCain is trying to plant the idea that Obama is simply an attention-craving crowd-pleaser.

Raising doubts about candidates have worked, most notably in 2004 when a shadowy group of President Bush backers called Swift Boat Veterans for Truth began running spots accusing Democrat John Kerry of embellishing his Vietnam War record. Kerry responded quickly, but the ads kept running, Republican-leaning talk shows kept promoting them and by mid-August Kerry was on the defensive.

McCain was the victim of similar tactics in 2000. He and his wife, Cindy, have a daughter whom they adopted from Bangladesh. In the weeks before the crucial South Carolina primary, voters got calls from so-called pollsters asking whether they were more or less likely to vote for him if they knew he had fathered an illegitimate black child. He lost the primary to George W. Bush.

Rick Davis, a McCain adviser, called it "the perfect smear campaign."

McCain's dangerous strategy

The strategy has risks. Some Republicans worry that a negative campaign will undermine his appeal, particularly with independent voters. And if voters find that Obama's image doesn't match the one McCain is peddling, they may reject him, a lesson Jimmy Carter learned in 1980 when he painted Ronald Reagan as dangerous and out of touch.

"In the end, Reagan didn't fit that image," Louden said. "That could happen again, if people hear Obama speak and say, 'He sounds reasonable.' "

Others said that as long as Obama is the candidate who needs to prove himself, voters will pay little attention to McCain -- angry or not.

"John McCain is simply not a relevant variable in this election," said Ken Goldstein, who directed the University of Wisconsin's advertising project.

Obama offered a rejoinder Thursday. "So far all we've been hearing about is Paris Hilton," he said in Iowa. "I do have to ask my opponent: Is that the best you can do? Is that what this election is really all about? Is that worthy of the American people?"

The Associated Press and McClatchy News Service contributed to this report.