With the first debate behind them, U.S. President Barack Obama and former Massachusetts governor Mitt Romney have resumed campaigning in Denver, Colorado, site of Wednesday's matchup.

Mr. Obama appeared at a rally where he accused Romney of changing his campaign positions. He said presidential candidates owe Americans “the truth.”

Mr. Romney made a surprise appearance at the Colorado Conservative Political Action Conference in Denver, where his sons were scheduled to speak. He called Mr. Obama's policies “trickle-down government.”

Later in the day, Mr. Romney holds a rally in Virginia with his running mate, Congressman Paul Ryan. Mr. Obama will travel later to Wisconsin, Mr. Ryan's home state.

Overnight polls by CNN and CBS show a majority of respondents feel Mr. Romney won Wednesday's debate. CNN's poll of registered voters said 67 percent of respondents felt Romney had won. CBS's poll of undecided voters found 46 percent believe Mr. Romney won, 22 percent believe Mr. Obama won, and 32 percent say they tied.

During the debate former Massachusetts governor Romney said Mr. Obama's policies have weakened the American economy and increased the national debt. He contended the president, if re-elected, would increase taxes and raise government spending to worsen the federal deficit.

Mr. Romney said middle-income Americans have been “buried” or “crushed” under high taxes. He contends tax rates on both corporations and individuals must be reduced.

Mr. Obama countered that Mr. Romney's tax plan would favor wealthy Americans and force severe cutbacks in important domestic programs.

The president says the first role of the federal government is to “keep the people safe,” but it also should create “frameworks” in which people can succeed. He noted that, in the past, the government has helped create railroads, research institutions and educational institutions.

The two men also sparred about the health-care reform law Mr. Obama pushed through Congress. Mr. Romney once again pledged that he would repeal the law, commonly known as “Obamacare,” if he were elected. He criticized the president for focusing on health care rather than the economy during Mr. Obama's first years in office.

Mr. Obama said the need to reform the U.S. health-care system was and is a key issue for all Americans — business owners and individuals.

In his closing statement, the president said he wants to expand the accomplishments of his first four years in the White House. He said he will work for change just as hard in a second term as he did in his first.

Mr. Romney, who had the last word in the nationally televised debate, said re-electing the president would mean more hardship for the American middle class.

The two candidates will meet for another debate on October 16 – a town hall-style session in which they will take questions from audience members.