Gabriel Bouys, Getty Images
Republican presidential hopefuls Mike Huckabee, left, Ron Paul, John McCain and Mitt Romney participate in a 90-minute CNN debate at the Ronald Reagan Presidential Library on Wednesday.

SIMI VALLEY, Calif. — There may have been four GOP contenders for the White House on stage Wednesday, but the debate before so-called "Super-Duper" Tuesday was really only between two of them — newly anointed front-runner John McCain and Mitt Romney.

The pair sparred several times during the 90-minute CNN debate at the Ronald Reagan Presidential Library here — especially over whether Romney had ever supported setting timetables for pulling out of Iraq — much to the frustration of the other Republicans still in the race, former Arkansas Gov. Mike Huckabee and Texas Rep. Ron Paul.

And although Romney's advisers said afterward they were pleased with his performance, much of their time in the post-debate "spin room" was spent deflecting questions about why the former Massachusetts governor has yet to buy television commercials in any of the 20-plus states, including Utah and California, that have voting Tuesday.

McCain, who seized the title of the man to beat in the race for the Republican nomination with his victory Tuesday in Florida's winner-take-all primary, was endorsed before the debate by longtime front-runner and former New York City Mayor Rudy Giuliani. McCain is expected to be endorsed today by California Gov. Arnold Schwarzenegger.

There was little new ground covered in the debate, but sparks flew between McCain and Romney over the Iraq question. Romney said he'd never supported setting a deadline and accused the Arizona senator of "Washington-style old politics, which is to lay a charge out there regardless of whether it's true or not" in the Florida race.

McCain countered by suggesting Romney was unwilling to put his reputation on the line by supporting the war during what he said was a critical time, when the newly elected Democratic majority in Congress was pushing for a pullout from Iraq.

And McCain went on, suggesting that Romney has spent millions of dollars of his own money on attack ads, against Huckabee in Iowa and McCain in New Hampshire. Romney lost Iowa to Huckabee and New Hampshire to McCain.

"Your attack ads, my friend, have unfortunately set the tone for this campaign," McCain said.

Paul, a one-time Libertarian candidate for president and an opponent of the war in Iraq, made it clear he was tired of listening to the bickering. "I find it rather silly, arguing the technicalities of a policy you both agree with," Paul said. "The dollar is crashing and you're talking about those technicalities of who said what, when."

Huckabee, who started the debate by insisting he was still in the running for the nomination, complained, too. "I didn't come here to umpire a ball game between these two," the Southern Baptist minister said.

Charlie Black, a senor adviser to McCain, told reporters his candidate clearly won the debate. "I thought Romney looked pretty defensive," Black said. He said that Huckabee is competitive in more "Super-Duper" Tuesday states than Romney, suggesting Romney could win only Massachusetts and Utah, where he turned around the troubled 2002 Winter Olympics in Salt Lake City.

But Romney spokesman Kevin Madden said Romney would be competitive in a number of other states, including Missouri, Minnesota, Illinois and Colorado. Romney is set to campaign in California and Colorado before heading to Utah on Friday to attend Saturday's funeral for the late LDS Church President Gordon B. Hinckley.

Madden and other Romney advisers refused to say whether the campaign would buy any television time in any of the "Super-Duper" Tuesday states. "We haven't made a decision. We haven't bought any ads — yet," Madden said. The issue isn't money or competitiveness, but strategy, Madden said.

Romney is worth an estimated $350 million and has poured millions of his personal fortune into the campaign, possibly twice as much or more than the $17 million he had loaned his campaign by Sept. 30, 2007. Black said McCain expected Romney to continue in the campaign for at least several more weeks after next Tuesday's primaries.

The candidate who left the race Thursday, Giuliani, dropped out after finishing a dismal third behind McCain and Romney in Florida, a state he'd banked on winning to jump-start his campaign.

Asked if his endorsement of McCain meant the end of Romney's presidential run, Giuliani said, "My endorsement means my endorsement. It's a positive endorsement for a great American and a person who is a great friend of mine who I believe is, at this point, the best qualified person to be president of the United States."

Giuliani told reporters he had long considered McCain the party's best choice — after himself, of course. "Obviously, I thought I was that person. The voters made a different choice," he said. And had he backed another candidate after making public statements to that effect in the past, Giuliani told reporters, "you would say I was flip-flopping."

That was as close as he came to directly criticizing Romney, whose positions on a number of key conservative issues, including abortion, have changed recently. McCain, the former mayor said, "came from way behind to go way ahead and once again displayed his tenacity, his courage" and his ability to get things done.

Giuliani said McCain, like him, wants to build a stronger and broader Republican party that embraces "all races and all religions in all 50 states." He promised to campaign for McCain in New York and anywhere else he was asked.

McCain accepted the endorsement with his wife, Cindy, by his side, and promised, "it will be a clear choice this November." But he stopped short of saying there could be a McCain-Giuliani ticket on the general election ballot, noting his ego was not big enough to make that prediction.