RACINE, Wisconsin (Reuters) - Republican White House hopeful John McCain’s campaign accused Democrat Barack Obama on Thursday of playing racial politics in some of the most biting back-and-forth of the presidential campaign.

The negative twist in the campaign for the November 4 election was prompted by a McCain television advertisement on Wednesday that called Obama a celebrity akin to star-crossed U.S. personalities Britney Spears and Paris Hilton.

In response, Obama said McCain was trying to scare voters away from him by pointing out he has “a funny name, and he doesn’t look like all the presidents on the dollar bills and the five dollar bills.”

Obama, whose father was Kenyan, would be the first black U.S. president. Only white men, most of them former presidents, are on U.S. paper currency.

“Barack Obama has played the race card, and he played it from the bottom of the deck. It’s divisive, negative, shameful and wrong,” McCain campaign manager Rick Davis said in a written statement.

Obama fired back during a town hall meeting in Cedar Rapids, Iowa, saying the attacks did not help voters deal with the array of problems they face.

“You’d think we’d be having a serious debate but so far all we’ve been hearing about is Paris Hilton and Britney Spears. I do have to ask my opponent: Is that the best you can come up with?” Obama said.

He said McCain had pledged to run an honorable campaign but had fallen back into “these negative ads, these negative attacks.”

But McCain said “we’re proud of that commercial” in speaking to a friendly audience at a town hall meeting in the battleground state of Wisconsin.

Republican presidential candidate Senator John McCain is shown during an energy policy speech at the University of Nevada Las Vegas, June 25, 2008. REUTERS/Steve Marcus/ Las Vegas Sun

“I admire his campaign, but what we are talking about here is substance and not style. And what we’re talking about is who has an agenda for the future of America. Campaigns are tough, but I am proud of the campaign that we have run,” McCain said.

UNDERDOG

The McCain campaign is trying to shake up a race that currently favors Obama at a time when the U.S. economy is weak, the U.S. military is stretched fighting two wars, and the annual budget deficit is approaching a half trillion dollars.

The McCain campaign believes the 71-year-old Arizona senator is the underdog but that the race is close and is trying to paint Obama as an inexperienced lightweight.

McCain went through a point-by-point litany of questions about Obama’s positions on taxes, energy and the Iraq war.

Noting Obama’s opposition to offshore oil drilling, he said his Democratic rival had urged Americans to make sure their tires were properly inflated as a way to increase gas mileage.

“Yesterday, he suggested that we put air in our tires to save on gas. My friends, let’s do that. But do you think that’s enough to break our dependence on Middle Eastern oil? I don’t think so,” he said to chuckles from the crowd in this Milwaukee suburb.

The “celebrity” television ad showed spliced images of Spears and Hilton with video of Obama addressing 200,000 Germans in Berlin last week.

The McCain side defended the ad, which generated much publicity, and said the Obama camp was over-reacting.

“It celebrates the excitement that he has generated, that is certainly more akin to the excitement that a celebrity generates than a normal politician,” McCain senior adviser Nicolle Wallace said on MSNBC.

But Obama adviser Robert Gibbs said on NBC’s “Today” show that McCain is “running an increasingly dishonorable campaign.”

“The McCain campaign has very clearly decided that the only way to win this election is to become very personal and very negative. We believe that people will see that as nothing more than the same old politics and the same old policies of the last eight years,” he said.

Both candidates vying to succeed President George W. Bush have said in the past they planned to run campaigns that would stay away from negative attacks and mud-slinging that have marked some presidential contests in recent years.