With two more presidential debates before the Nov. 6 election, senior aide David Axelrod said the Obama campaign would adjust its strategy as a result of the debate.
"We are going to take a hard look at this and we are going to have to make some adjustments as to where to draw the lines in these debates and how to use our time," he told reporters.
Democratic sources said Obama raised more than $100 million in September in another sign of his financial strength going into the last month of the campaign.
Romney prepared for the Denver encounter with days of mock debates and was more ready to go on the offensive against Obama in detailed discussion on taxes, jobs, energy and the budget deficit.
Obama is unlikely to add "huge amounts of additional prep time," for the two other debates, on Oct. 16 in New York and on Oct. 22 in Florida, Axelrod said.
Part of the Obama strategy will be to attack Romney for what the Democratic campaign says are untruthful statements during the debate on his tax plan, Medicare and deficit cutting, as well as pressing him on what appeared to be changes in position on issues like bank regulation.
"We obviously are going to have to adjust for the fact of Mitt Romney's dishonesty," senior advisor David Plouffe said. "It's hard to remember a time in American politics when you have someone who is a major nominee for the presidency being that fundamentally dishonest about core parts of his campaign platform."
Obama spoke to a large crowd in Madison, Wisconsin, on Thursday afternoon that his campaign said was 30,000 strong.