US President Barack Obama woke up to stinking reviews of his debate performance Thursday, then set out to stamp on Republican Mitt Romney's sudden momentum 33 days before the election.

Obama turned in a lethargic and sometimes irritable performance in Denver on Wednesday night, allowing a pumped-up Romney an opening in a White House race that had been trending away from the Republican after weeks of gaffes.

The president's aides went on the attack early Thursday to try and turn the narrative around, insisting that Romney's showing was littered with inconsistencies and untruths -- albeit ones left unchallenged by Obama.

"Governor Romney came to give a performance and he gave a good performance and we credit him for that," senior Obama campaign strategist David Axelrod told reporters on a conference call.

But Axelrod charged that Romney was "completely untethered from the truth" and questioned whether snap polls showing the Republican won the debate would be sufficient for him to close the gap on Obama in battleground states.

"It was a very vigorous performance but one that was devoid of honesty," Axelrod said. "He may have won the Oscar for his performance last night, but he is not going to win the presidency."

Rapper tried to change the mood music for Obama fans gathered at a chilly lakeside park for his first post-debate event in Denver, pounding out hits like "It's A New Day" and "Don't Stop Believin'".

Obama was later to head to the Midwestern battleground of Wisconsin, where he is up by seven percent in the RealClearPolitics average.

Romney was linking up with vice presidential running mate Paul Ryan to hit another vital swing state, Virginia, which some analysts believe could be the decisive battleground in 2012 and where Obama is up by around three percent.

A fundraising email sent out by the Republican nominee on Thursday encapsulated the mood in his camp with its title "Victory in Sight."

Among conservatives, who have often despaired of their sometimes leaden champion during this campaign season, there was relief and almost euphoria at Romney's confident showing.

"Barring revelations by the Obama campaign that Mitt Romney has an identical twin, whoever that guy representing the GOP ticket was in Denver has just given the United States a real presidential election. At last," the Wall Street Journal's Daniel Henninger wrote.

William Kristol of the conservative Weekly Standard went further, saying Romney had "stood and delivered the best debate performance by a Republican presidential candidate in more than two decades."

As tens of millions of Americans tuned in to watch the biggest event so far in the White House race, Romney appeared crisper and clearer than the president, who seemed tired after an exhausting four years at the helm amid the fallout of the worst economic crisis in decades.

"There's no question in my mind that if the president were to be re-elected you'll continue to see a middle-class squeeze with incomes going down and prices going up. I'll get incomes up again," Romney said.

"(With Obama) you'll see chronic unemployment. We've had 43 straight months with unemployment above 8 percent. If I'm president, I will create -- help create 12 million new jobs in this country with rising incomes."

Obama hit back by suggesting Romney would make $5.4 trillion in tax cuts geared towards the wealthy and said his Republican foe hadn't ventured which loopholes in the tax system he would close.

"Governor Romney has a perspective that says if we cut taxes skewed toward the wealthy and cut back regulations, we'll be better off. I have a different view," the Democratic incumbent said, calling for "economic patriotism."

The question now is whether Romney's stronger debate performance has changed the minds of enough wavering voters in key swing states to give the Republican challenger a real chance on November 6.

Opinion polls in the coming days will provide the first clues.