To many Democrats, Obama was missing that fire in the first debate. Because of that performance, the president acknowledged coming into Tuesday that he would have to be more aggressive.

Sen. John Kerry of Massachusetts, the man who played Romney in debate prep, said Obama could have been more confrontational.

"The president could have been more aggressive tonight given some of the things that Mitt Romney said," Kerry told CNN's Jessica Yellin. "He held back on a few occasions."

Republicans acknowledged the president's change in style in the second debate.

"We all knew the president would be more aggressive tonight. The president said he was going to be and I think his base probably appreciated that," Sen. Rob Portman of Ohio told CNN's Jim Acosta. "I don't think the undecided voter in Ohio thought it was very effective, but the president was on the attack."