DENVER -- Maybe it was the pre-debate game of Jenga that loosened up Republican presidential nominee Mitt Romney.

Whatever it was, the GOP's hope for ousting President Obama in November was on his game Wednesday night at the first presidential debate, lobbing blow after blow at his Democratic opponent on taxes, health care and his subsidies for failed solar energy firms. Romney acted very much like the impassioned candidate for which his party has been pining throughout the campaign and he achieved an aim few expected him to reach: He kept the president on the defensive, looking irritated throughout the 90-minute exchange.

"Romney had the eye of the tiger and simply won this debate because he seemed better prepared and more enthusiastic," Republican strategist Ron Bonjean told The Washington Examiner. "He was nimble and set an aggressive pace while he kept Obama on the defensive."

The president started off aggressively, going after Romney over what he said was a $5 trillion tax cut for the wealthy and charging that his Republican rival could never simultaneously cut taxes, increase defense spending and reduce the nation's budget deficit as Romney claims he will.

"How we pay for that, reduce the deficit, and make the investments that we need to make, without dumping those costs onto middle-class Americans, I think is one of the central questions of this campaign," Obama said.

But Romney responded forcefully, displaying a passion that many Republicans have long been hoping to see. He denied proposing a $5 trillion tax cut, said he has no plans to reduce the taxes on the wealthy and would actually lower taxes on the middle class.

"Under the president's policies, middle-income Americans have been buried," Romney said, echoing a line from Obama's gaffe-prone vice president, Joe Biden. "They're just being crushed. Middle- income Americans have seen their income come down by $4,300. This is a tax in and of itself. I'll call it the economy tax. It's been crushing."

Romney virtually reprised a Ronald Reagan moment from the 1980 debate, when Reagan turned the tide against President Jimmy Carter by asking Americans if they were really better off than they were four years earlier.

"Look at the evidence of the last four years," Romney said. "We've got 23 million people out of work or [who] stopped looking for work in this country. When the president took office, 32 million people on food stamps, 47 million on food stamps today. Economic growth this year [is] slower than last year, and last year slower than the year before."

Even on health care, an issue on which the Obama campaign believes Romney is vulnerable because he instituted in Massachusetts reforms very similar to those later imposed nationally by the president, Obama appeared defensive.

Democratic strategist Christopher Hahn told The Examiner that Obama "started slow but heated up near the middle."

But Democratic-leaning pollster John Zogby said Romney was the clear winner. "Mitt won big tonight ... Romney came out to play hard."

And University of Virginia political science professor Larry Sabato said, "Romney won the first debate. I don't think it was particularly close."

Romney and Obama arrived at the Magness Arena at the University of Denver with polls showing the race tighter than ever, even in battleground states in which the president had started to pull ahead. But the two candidates on Thursday will begin separate tours of those battleground states, including Virginia, with Romney for the first time feeling momentum.