U.S. President Barack Obama has reacted to Mitt Romney's "47 per cent" remarks in an appearance on the Late Show with David Letterman on Tuesday night.

While the Republican presidential nominee was trying to contain the fallout of his controversial comments that he wasn't worried about the 47 per cent of Americans that don't pay taxes and believe they are "victims," Obama cracked jokes with the television show host and hit back at Romney.

"One of the things I've learned as president is you represent the entire country," Obama told Letterman. "And when I meet Republicans, as I'm travelling around the country, they are hard working, family people who care deeply about this country. And, my expectation is, that if you want to be president, you have got to work for everybody. Not just for some."

Romney's remarks at a May fundraiser were captured on hidden camera and released to the media this week. He said that 47 per cent of Americans don't pay taxes and believe they are entitled to extensive government support. They also view themselves as victims, he said.

"My job is not to worry about those people," Romney said at the Florida event.