Local reaction to the first presidential debate in Colorado history was strongly positive, as supporters of both President Barack Obama and Republican challenger Mitt Romney claimed victory for their candidates.

An estimated 50 million Americans watched the debate on TV, in which Romney rejected the claim that he will cut taxes for the richest and called for the creation of new jobs and reduction of national debt.

"My plan is not like anything that's ever been tried before," he said. "My priority is putting people back to work."

President Obama disagreed, saying Romney's plan is the same as what created the financial crisis and triggered the 2008 American market crash.

"If you cut taxes by 5 trillion US dollars and add 2 trillion dollars to a military that's not asking for it ... math, common sense and history prove this is not a recipe for economic growth," Obama said.

National polls showed Romney trailing Obama by a slight margin across the country and in Colorado, one of the key "battleground" states, along with Florida and Ohio, that will decide the upcoming 2012 election.

The televised, 90-minute debate was conducted inside the sold-out 6,000 seat University of Denver's (DU) Ritchie Center, where the audience was cordial and reaction restrained. Students participated in a "Presidential Debate" lottery to get tickets to the prized event.

But outside the debate hall, the DU campus was festive and loud, as thousands of students and political participants cheered while watching the debate on two massive TV monitors as part of DU's "Debatefest" event.

The day-long Debatefest attracted an estimated 10,000 participants, while thousands more participated in rallies and demonstrations on the streets surrounding the university campus.

"I think it's awesome," said Ruoxi Zhao, a second-year accounting major from China, referring to her close-up view of the American political process. "I can't believe it's right here on our campus."

Security was tight around the 125-acre DU campus and included the closure of nearby highway I-25. That didn't stop thousands of citizens, who descended on the university carrying signs like "Two Corporate Losers," referring to both Obama and Romney.

Police, dressed in riot gear, anxiously followed groups of students marching down streets while carrying signs and shouting slogans on bullhorns. There were no reports of arrests or damage to property.

On campus, large groups of food vendors offered lemonade, french fries and burgers to an audience who spent the afternoon mingling, talking politics and joining in the event.

Barbara McClelland, a third generation Colorado voter, carried a sign that reads "Colorado Cowgirls for Obama." McClelland said in 1908, her grandmother rode a horse from Silverton, a small mining town west of Denver, to Denver to vote.

"We're rugged people here, and Colorado was the first state to get women the right to vote," she said. "We love the political process and Obama is our man."

Bill Nelson, another Denver resident, carried a sign saying, "Fire Obama." Nelson said he was thrilled by the Debatefest environment.

"It's a chance for the people to get involved in the process, to discuss politics, to debate," Nelson said. "No matter who you support, the exchange of ideas and dialogue is inspiring."

The University of Denver, established in 1864, is among the top 100 universities in the United States. Wednesday's debate was the first of three scheduled debates between the presidential candidates prior to November's election.