Instead, Romney blasted the president's economic record, noting a study heavily circulated by his campaign that showed nearly half of recent college graduates were either without jobs or underemployed.

"Unacceptable. Unthinkable. This president has failed on the No. 1 measure he said was important for Americans: good jobs," Romney said.

The pair seemed to capture the partisan crowd and at times riffed off one each other.

Speaking of the proposed Keystone XL oil pipeline, Rubio said the Canadians had a choice between routing valuable oil through either the United States or China.

"Which direction do you think the president will chose? China. Which direction do you think Mitt Romney will chose? America," Rubio said.

That prompted Romney to say that — in a self-admitted "moment of rhetorical flourish" — he wanted to build the pipeline with his own bare hands.

Rubio and Romney showed off a similar rapport on voter identification laws, with the pair trading stories about why they believed the controversial legislation was necessary for states to adopt. Rubio joked about needing to use I.D. to purchase an exercise bike — "My wife said I was looking a little senatorial," he quipped — while Romney told a story about machine politics and voter fraud in Boston.

The Florida lawmaker also previewed how he might work as an attack dog on behalf of the Romney campaign, using his personal history as the son of Cuban immigrants to question the president's economic policies.

Rubio said Obama is "telling Americans that the reason that why they're struggling is other people are doing well" and that the president believed "the way up the ladder is pulling other people down."

"He doesn't know what he's doing," Rubio said of the president.