WASHINGTON — Republican Senate candidate Ken Buck suddenly elevated the culture wars from minor player to center stage in the Senate race today when he compared homosexuality to alcoholism in a nationally televised debate.

Appearing with Democratic Sen. Michael Bennet in a 27-minute showdown on Meet the Press, Buck responded to a question from host David Gregory by saying that he believed homosexuality was a choice but had limited biological influences “like alcoholism and some other things.”

Buck said after the debate that he “wasn’t talking about being gay as a disease” but also said of his remark that “there’s no doubt there will probably be a commercial on something like that” from Democrats.

Tough questioning by Gregory and a national television audience turned the debate into a significant and uneven test for both men, with Bennet struggling to explain his relationship to President Barack Obama’s agenda and Buck defending a series of campaign flip-flops.

An admittedly nervous Buck at one point defended his support for extending the Bush tax cuts for the wealthiest Americans by mentioning three times that they would pay for themselves by “growing government.”

He eventually corrected himself: “I’m sorry, growing the economy.”

“I’ve got that boot in my mouth again,” he said afterward.

Although it’s uncertain what impact that debate will have on Colorado voters, the appearance represents the most exposure the two candidates will have to a national audience.

A Politico.com story called Buck “shaky” and a headline on a Hotline On Call story said the appearance “opens (the) door for Bennet.”

Bennet’s toughest moment came after Gregory played a clip of the appointed Senator noting that the nation had nothing to show for its record $13 trillion debt and then asked Bennet to justify his vote for the $787 billion stimulus package.

“You have been in lockstep with this President,” Gregory said. “Congressional Quarterly says you voted with the President 97 percent of the time.”

Bennet shot back: “When I agree with the President, I agree with him. When I disagree with him, I disagree with him. He’s done some things that were not helpful to Colorado and I fought back.”

The debate was notable in part because, other than abortion, cultural hot-button issues have played a relatively minor role in a race that until now was centered on fiscal issues, the debt, and the size of government – themes that have resonated with voters angry over the shaky economy and the growing reach of government.

Buck conceded as much following the appearance, as he worked to minimize the impact of some of his comments.

“In 800 meetings, interviews, events, I’ve never been asked that question” about homosexuality, Buck said. “Colorado voters aren’t focused on whether it’s a choice or whatever.”

Denver Post political editor Curtis Hubbard contributed to this report.