St. Petersburg, Fla. ? Former Arkansas Gov. Mike Huckabee came under attack for the first time in a Republican presidential debate Wednesday, a sure sign of how his recent rise in polls has helped turn the race into a free-for-all five weeks before voting starts.

The debate, sponsored by CNN and the Internet-video phenomenon of YouTube, spun around a format of free-wheeling queries from viewers who had offered about 5,000 video-questions for candidates – including one from a man shown cocking a gun as he asked the candidates what sort of guns they own.

Huckabee was questioned about his willingness to raise taxes as governor and his support of college scholarships for meritorious children of illegal immigrants – two positions that could hurt him among conservatives and perhaps slow the gains he’s made in recent weeks.

“You know, when you get attacked, it’s not always bad,” Huckabee said to laughs from the Republican audience. “It’s like my old pastor used to tell me: When they’re kicking you in the rear, it’s just proving you’re still out front.”

Just hours before the first Republican debate in seven weeks started, a new poll in Iowa – whose Jan. 3 caucuses kick off presidential voting – showed Huckabee pulling ahead of former Massachusetts Gov. Mitt Romney, the longtime Iowa front-runner, for the first time, 28-25 percent. Former New York Mayor Rudy Giuliani was a distant third at 12 percent, and former Tennessee Sen. Fred Thompson pulled 11 percent.

The poll had a small sample and Huckabee’s edge might disappear inside the 3.5 percent plus-or-minus margin of error. But his showing underscored the dynamic that fed the two-hour debate: that any one of five men now appear credible candidates to win the Republican nomination – Giuliani, Huckabee, Romney, Thompson or Sen. John McCain of Arizona. Each delivered standout moments at Wednesday night’s debate.

Several candidates took shots at one another, with most working to shore up support from conservatives on issues such as immigration and taxes.

Giuliani and Romney, for example, picked up exactly where they left off last weekend on the campaign trail, accusing each other of being soft on illegal immigrants.

Romney accused Giuliani of turning New York into a sanctuary for illegal immigrants. Giuliani in turn accused Romney of having a “sanctuary mansion” by allowing a firm with illegal immigrant employees to do work there.

Huckabee was pressed to explain his support for scholarships for children of illegal immigrants.

He said that he’d favored a bill, which didn’t pass the Arkansas legislature, that would’ve allowed college scholarships to children who attended school in the state since they were 5 years old, maintained an A average, and were applying for citizenship. “They had to earn it,” Huckabee said.

Romney ripped him, likening him to Massachusetts liberals.

“That’s not your money, it’s the taxpayers’ money,” Romney said.

Huckabee countered that, “in all due respect, we’re a better country than to punish children for what their parents did.”

Thompson went after two rivals simultaneously, catching the audience and candidates by surprise when CNN unveiled his new attack-ad video to rip rivals where other candidates displayed short videos only to promote themselves.

Thompson’s video showed Romney supporting abortion rights in 1994 and Huckabee as governor saying that he’d accept some tax increases.

Debate moderator Anderson Cooper looked startled: “What’s up with that,” he asked Thompson.

“I wanna give my buddies here a little extra air time,” a grinning Thompson replied.

Cooper said the video deserved a response.

Romney apologized for his former pro-abortion stand.

“I don’t know how many times I could tell it, I was wrong, all right?” Romney said. “I was effectively pro-choice when I ran for office. … I was wrong and I changed my mind. I’m proud to be pro-life, and I’m not going to be apologizing to people for becoming pro-life.”

“I cut taxes 90 times,” Huckabee said. “The sales tax was one penny higher. But I did do a number of tax cuts that helped a lot of people all over the place, like eliminating the marriage penalty, doubling the child care tax credit, getting rid of capital gains on the sale of a home, cutting capital gains on other things.”

The candidates split when asked to pledge to veto any tax increase.

Four promised an anti-tax veto: Giuliani, Huckabee, Romney and Rep. Tom Tancredo of Colorado. The other four all said they opposed tax increases but refused to make the pledge: Thompson, McCain, Rep. Duncan Hunter of California, and Rep. Ron Paul of Texas.

The issue could be complicated, however; many Bush tax cuts expire at the end of 2010, and it wouldn’t take legislation to let them expire – thus raising taxes.