JOHN McCain wants the presidential campaign to be about Barack Obama - that's why he talks about him so much. 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. Three months before Election Day, McCain's strategy raises this question: Will voters vote for the scold? A new ad launched Wednesday suggests Obama is nothing more than a lightweight celebrity. Images of him speaking to a 200,000-strong crowd in Berlin last week are interspersed with shots of Britney Spears and Paris Hilton. An announcer intones: “He's the biggest celebrity in the world. But, is he ready to lead?” No doubt Obama has fame. He fills political venues with people. He breaks fundraising records with a massive donor base. He does not have a name recognition problem. But Obama himself concedes that his challenge is getting voters to see him as president “It's a leap, electing a 46-year-old black guy named Barack Obama,” he said Wednesday. But McCain can't compete with his Democratic rival on popularity. Instead, the Republican contender is working on sowing doubts about his opponent: that Obama is not tested, not ready to lead and too out of touch with the public. “The Obama campaign does a wonderful job of presenting their candidate in the most popular light that they can get, and they do a very good job at it,” McCain campaign manager Rick Davis told reporters Wednesday. “I'm going to let the American public decide what is negative and what is not negative,” he added. “But I'm going to do everything in my power to protect my candidate and to define the race in terms that I think are appropriate.” In public, McCain's criticism of Obama is not as sharp: “Sen. Obama is an impressive speaker, and the beauty of his words have attracted many people especially among the young to his campaign,” he said Wednesday. “I applaud his success. All Americans should be proud of his accomplishments. My concern with Sen. Obama is with issues big and small, what he says and what he does are often two different things.” For his part, Obama has managed to keep his hands cleaner on negative ads, though he has counter-punched. Instead, outside groups that support him have run commercials against McCain. On Thursday, a coalition including MoveOn.org and the Sierra Club were launching ads critical of McCain's stance on energy and gasoline prices. Some Republicans welcomed McCain's confrontational strategy. New Hampshire Republican Chairman Fergus Cullen said Republicans in his state “like to see the McCain campaign on offense.” 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. McCain is popular in his own right. He ran for president in 2000 and has built his image as a maverick, challenging President George W. Bush and fellow Republicans on some high-profile legislation. But some Republicans worry that a negative campaign will undermine his appeal, particularly with independent voters. 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, according to a study of political commercials by the Advertising Project at the University of Wisconsin. “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. Others maintain 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, a political scientist and director of the advertising project. In working to sow doubts about Obama, the McCain campaign has not employed a single line of attack. Its heaviest ad placements have focused on energy, blaming Obama for high gas prices and depicting him as a tax raiser who opposes expanded oil exploration. But it also has launched ads criticizing Obama's stand on the Iraq war and his decision not to visit wounded soldiers in Germany. Obama said he did not want the visit to be seen as political. The Iraq ads have received widespread media attention, although they appeared only a handful of times in a few markets. “This careening from message to message makes them look like they don't have one specific thing they want to say about this guy and that there is no centralized theme, there is no centralized message,” Republican pollster Tony Fabrizio said. “And that is most concerning.” Obama is projecting confidence, but he is not ready to ignore McCain, though. In back-to-back days, he has retaliated with ads attacking McCain. In both, he accuses McCain of engaging in “old politics” - a loaded phrase given that McCain turns 72 in late August. On Wednesday, an Obama ad characterized McCain's ads as “false” and “baloney.” It was unclear how broadly the campaign intended to air the ad, however, saying only that it would appear Thursday “in some markets.” But Obama also offered a personal rejoinder Wednesday. “He doesn't seem to have anything positive to say about me does he?” he said, campaigning in Missouri. “You need to ask John McCain what he's for not just what he's against.” – AP __