DENVER - Republican presidential nominee Mitt Romney re-emerged on the campaign trail Thursday energized after a breakout debate performance the previous night that many predict will give his campaign the shot of momentum it has been lacking.

"If this debate was a boxing match," Romney advisor Eric Fehrnstrom boasted, "the referee would have called it about an hour into the fight. Mitt Romney was the clear winner."

Romney campaigned in Denver early Thursday, insisting that the race would remain close. He then headed to Fishersville, Va., a small town in the center of that critical swing state, where he and vice presidential nominee Paul Ryan spoke to a wildly enthusiastic crowd estimated at more than 20,000. The rally was delayed by the long lines of traffic that swelled the throng, an apparent indication of the campaign's rising fortunes following the debate. "Last night was an important night for the country because people ... were able to listen to substance," Romney said. After promising to rejuvenate the American economy with tax breaks on the middle class and more sound energy policies, he said, "We can't afford four more years like the last four years."

The Republican nominee has been virtually even with Obama in national tracking polls, and though the president was starting to pull away in a handful of battleground states like Ohio, Romney aides and supporters said his powerful debate performance is likely to attract undecided voters and propel him higher in the polls.

"Undecided voters in Ohio wanted to hear more about where Mr. Romney was going to take the country and they heard that in this debate," Sen. Rob Portman, R-Ohio, who helped prepare Romney for the debate, told The Washington Examiner. "I think this is going to change the dynamics of the race."

Historically, polls have occasionally shifted, at least by a few percentage points, as a result of great -- or terrible -- debate performances.

In 1980, Republican presidential nominee Ronald Reagan was trailing Democratic President Jimmy Carter by 3 percentage points among likely voters until the two debated a week ahead of the election. After the debate, Reagan's standing rose by 6 points and he beat Carter.

Pundits and pollsters are now waiting to see if Romney's victory Wednesday will have a similar effect on voter preference.

"This will test whether debates can really change polls and election outcomes," University of Virginia political science professor Larry Sabato told The Examiner. "Odds are against it, but it is a possibility."

Obama campaign aides say despite the debate, they see no path to victory for Romney, specifically because of his swing state deficit, which they believe won't improve.

"We know in a very close race we have a small advantage in a lot of swing states," senior Obama adviser David Plouffe said after the debate concluded. "If Romney can't tie us or get ahead of us in Ohio, Nevada and other swing states, that's all that matters."

But other Democrats disagree.

Doug Schoen said Romney's successful debate performance and Obama's seemingly lackluster effort changed the dynamics of a race many saw favoring Obama.

"The race is now a tie," Schoen said.

Now, Obama needs to do well in the next debate, a town hall-style event on Oct. 16, he said.

"Obama will be alive and well in the next debate," Schoen said. "A town hall which will play to his strengths. Game is on, not a game changer."