Earlier, Mr Obama made an appearance on the Daily Show with Jon Stewart. He said the US would "fix" security overseas after a deadly Libya attack. Stewart asked Mr Obama about the administration's "confused" response to the attack on a US consulate in Benghazi, Libya on 11 September. The US ambassador to Libya and three other Americans died in the attack, which remains at the centre of the campaign debate ahead of a foreign policy debate in Florida on Monday.
Mr Obama told Stewart his administration was still piecing together the evidence.
"The government is a big operation. At any given time, something screws up and you make sure you find out what's broken and you fix it," he said.
Mr Obama also repeated his wish to close the prison at Guantanamo Bay naval base in Cuba, a first term promise he has been criticized for not yet carrying out.
The dinner was overseen by Cardinal Timothy Dolan, the president of the US Conference of Catholic Bishops, which has clashed with the administration over contraception provisions in Mr Obama's health care law. Cardinal Dolan has said he received "stacks of mail" protesting against Mr Obama's invitation to the dinner, but he sought to avoid playing political favourites. The cardinal delivered benedictions at both the Republican and Democratic national conventions in 2012.
Ahead of his reunion with Mr Obama, a daily Gallup tracking poll of likely voters suggested Mr Romney had increased his lead nationally. However, a series of other polls show a much tighter race.
Mr Romney announced on Thursday that his campaign was leaving North Carolina, believing his victory was assured there. He is currently polling an average of six points ahead of Mr Obama in the state.
Mr Obama also benefited from new polling on Thursday, with a Pew Hispanic Center poll suggesting three-quarters of Catholic Latinos back the president. The president picked up the backing of rock star Bruce Springsteen, as he did in 2008. Springsteen campaigned for Mr Obama on Thursday in Ohio with former President Bill Clinton.
"For 30 years I've been writing about the distance between the American dream and American reality," Springsteen said, reading from a statement.
"Our vote is the one principal way we get to determine that distance."