An aggressive Andrew Romanoff jabbed continuously at U.S. Rep. Mike Coffman during the candidates’ third formal debate on Tuesday night in Denver, criticizing the incumbent Republican for everything from opposing birth control methods throughout his lengthy political career to attacks on the Democratic challenger’s Ivy League education.

A more reserved Coffman — in stark contrast to his demeanor in previous debates, when he swung equally hard at Romanoff — slammed Romanoff for “fundamentally dishonest” attacks on his record while repeatedly invoking his military service and votes he says run counter to the portrait foes are painting of him in heavy advertising.

The two are engaged in what could be the closest congressional race in the country this year, bidding for the chance to represent the evenly divided 6th Congressional District, which covers Aurora and suburbs in Adams, Arapahoe and a sliver of Douglas County.

The candidates clashed for an hour before a packed audience at the Denver Post auditorium in a debate sponsored by the newspaper and moderated by politics editor Chuck Plunkett and reporter Jon Murray, who is covering the race. Three more debates are scheduled before votes are counted, including one conducted entirely in Spanish at the end of October.

Romanoff, who represented a central Denver district in the Colorado House of Representatives for four terms in the last decade, referred repeatedly to his tenure as House speaker, when he said he worked across the aisle to solve problems rather than engage in partisan gamesmanship. Contrasting that record with Coffman’s, he said, “When I was speaker of the House, I disagreed with Gov. Owens,” a Republican. “Healthy debate is essential to the operation of our democracy, but you don’t shut down the whole government and jeopardize jobs when you can’t agree on a compromise.”

Coffman, who grew up in Aurora and served in the Legislature and as state treasurer and secretary of state before winning election to Congress six years ago, repeated a steady attack on Romanoff’s political ambition, wherever he calls home.

Romanoff, he said, “moved into Aurora not because he wants to live in Aurora but because he wants to live in Washington, D.C.,” and claimed there’s nothing wrong with pointing that out.

Earlier in the debate, asked why he moved into the district early last year, Romanoff said he was “excited to represent” Aurora, which is at the core of the redrawn 6th CD and criticized Coffman for his initial opposition to the district boundaries during the reapportionment process in 2011. “He didn’t want the responsibility of representing this diverse, highly competitive, evenly divided district,” Romanoff said. “I would be happy to relieve you of that responsibility.”

Coffman got in some digs at Romanoff’s resumé, which has included frequent mention of his degrees from Harvard and Yale in past debates.

“Speaker Romanoff, in debates you’ve pointed out sometimes that you’ve had a privileged life, God bless you, went to private prep school and on from there,” Coffman said, asking whether Romanoff would “stand against the teachers union” to support vouchers.

Romanoff said he doesn’t plan to support vouchers for private schools as long as those schools are able to discriminate and exempt themselves from testing requirements, and then swung back at Coffman.

“It’s actually you, Congressman, who has spent the bulk of this campaign talking about very little else — my school, my education, my family,” Romanoff added with a smile. “Thank God you haven’t picked on my dog yet. That is not at issue in this race.”

The candidates agreed about numerous questions — both oppose Amendment 68, a statewide ballot measure that would establish a casino in the district, and both said the federal government should establish clear rules so the state’s marijuana businesses can access banking — but they took opposing sides on gay marriage in Colorado, with Romanoff supporting it and Coffman opposing it, and questions about climate change.

During a rapid-fire “yes-no” portion of the debate, asked whether the candidates believe humans are “contributing significantly” to climate change, Romanoff said yes and Coffman said no, drawing gasps from the crowd. Then, asked whether “we can reverse climate change,” Romanoff replied “yes,” and Coffman murmured, “Don’t know.” Pressed by the moderators, he answered, “No.”

Given the chance to elaborate, Coffman said that he believes human activity has an impact but that “the science is not quite settled.” He added, “But I think we have to do everything responsible to bring down carbon emissions. Sometimes my worry is when we go too far, what happens is, we push, particularly manufacturing jobs overseas to a country like China that has no environmental rules. And those same products are made with greater carbon emissions that otherwise would’ve been made in the United States. I think there has to be a balance that has to be achieved there.”

Romanoff swung back a few minutes later, answering a question about green energy.

“We are never going to take the action we need to address climate change if we don’t recognize the problem,” he said. “Congressman Coffman made it clear tonight he does not recognize this problem, despite the overwhelming scientific consensus about the origins of climate change.” Congress, Romanoff continued, “could learn a lot from Colorado,” which has established requirements to generate power from clean energy sources.

Coffman said that his military tours in the Mideast are part of what leads him to support reducing dependency on foreign oil and called for more research on alternative fuels. Toward that aim, he said, he strongly supports the Golden-based National Renewable Energy Laboratory, a claim that drew a swift rebuke from Romanoff.

It is disappointing, Romanoff said, that “only in the course of a tough campaign” would Coffman announce his support for reduction in carbon emissions, while his record in Washington is exactly the opposite. “What matters, it seems to me again and again, is not what you say here but what you do there.”

After the debate, a spokeswoman for the Romanoff campaign said that Coffman’s statements sharpened the choice for voters.

“It’s nice to have clarity on a certain number of issues — climate change, gay marriage, a lot of things we’ve heard different statements in the past. We know where he is on those issues,” campaign communications director Denise Baron told The Colorado Statesman.

She said that Coffman’s answers on birth control and abortion were also telling.

“I’m always surprised when Congressman Coffman says that he supports access to birth control, given his 25 years of working to make it less available to women,” she said, adding that the question will be decisive among voters. “Access to birth control, the right to chose — these are fundamental, core values for the women of this district.”

A Coffman spokesman had an entirely different take on the debate.

“It’s clear that Andrew Romanoff is desperate,” said Coffman campaign manager Tyler Sandburg. “The entire night he spent attacking Mike Coffman. Mike Coffman was confident and clear and command of all the hard work he’s done for this district. It’s clear that Romanoff’s internal polling is not looking very good right now.”

Asked to reveal what that internal polling showed — there haven’t been any publicly released polls in the race — Sandburg demurred but claimed the Republican was confident.

“Our polling shows that voters are proud to have a representative that works across the aisle and gets things done. Mike’s leadership on the (Veterans Administration), in particular, demonstrates that he doesn’t waste time on partisan bickering in Washington, but focuses on and finds solutions to problems every American agrees need fixing,” Sandburg said.

“Romanoff’s increase negativity and incessant focus on attacking Mike, rather than defending his own record of tax increases, debt increases and a history of campaign tactics the Denver Post called ‘a shameful example of cynical politics at its worst’ is a pretty clear sign that he’s behind,” he added.

— Ernest@coloradostatesman.com