Reeling from a poor debate performance, President Obama on Thursday heightened attacks on Mitt Romney in hopes of getting his campaign back on course, accusing the Republican of duping voters with polished, but false promises about his economic agenda.

"When I got onto the stage, I met this very spirited fellow who claimed to be Mitt Romney," Obama told supporters in Colorado. "[T]he real Mitt Romney has been running around the country for the last year promising $5 trillion in tax cuts that favor the wealthy."

Republicans and Democrats alike declared the former Massachusetts governor the winner of the first presidential debate. Going into the forum, many expected Obama to prevail, but Romney shattered such prognostications by putting the president on the defensive early and often over his stewardship of the economy.

"Romney had the better night; he was energetic and lively, and Obama seemed sluggish and not particularly happy to be there," Democratic strategist Keir Murray conceded. "Obama has got to be quicker on the counterpunch."

Judging by a pair of speeches Thursday, Obama intends to dial up his attacks on Romney. Obama did everything short of calling Romney a liar on Thursday, and his campaign vowed the president would be more forceful in drawing contrasts with his Republican challenger.

"You see, the man on stage last night, he does not want to be held accountable for the real Mitt Romney's decisions ... If you want to be president, you owe the American people the truth," Obama said.

Vice President Biden, embracing the attack dog role, put it more bluntly, telling a partisan crowd that Romney not only was hiding his own tax returns from voters but also refusing to tell them how their tax rates would change during a Romney presidency.

The GOP candidate received high marks for framing Obama in the debate as a champion of "trickle-down government" who is stifling small business with an array of taxes and regulations. Political pundits predict Romney's performance will win him a bounce in the polls among undecided voters.

The challenge for team Obama is getting back to the message that gave the president a boost following the Democratic National Convention and had Republicans on edge going into the first presidential debate.

Obama on Thursday highlighted Romney's assertion in a private fundraiser that nearly half the country was dependent on the federal government -- a topic the president skipped entirely in the debate. Obama said the episode proves Romney "writes off half the nation before he takes office." At a campaign rally in Wisconsin, Obama said that Romney was "going to crack down on Sesame Street" but let Wall Street run amok -- a jab at Romney's pledge to eliminate federal subsidies for public broadcasters.

Obama's heightened feistiness comes as Democrats pile on the president for failing to deliver the performance they expected from him.

A prominent progressive not affiliated with the Obama campaign told The Washington Examiner, "I don't know who that was in the debate. Another performance like that would be a disaster."

Added Simon Rosenberg, a former campaign adviser to President Bill Clinton, "Romney changed the tone of the election last night. I think Obama is now aware he has to be more emotive and more high energy."