During a town hall at the University of Miami, Univision news anchor Jorge Ramos reminded Obama he promised in May 2008 "we will have, in the first year, an immigration bill that I strongly support."
Ramos pointed out Obama did not introduce immigration reform legislation during his first year and asked the president to "acknowledge that you did not keep your promise."
The president said when he took office in January 2009, his first priority was "making sure that we prevented us from going into a Great Depression" through emergency measures "that took up a huge amount of time in the first year."
"But even in that first year, one of my first acts was to invite every single member of Congress who had previously been supportive of comprehensive immigration reform, and to say to them, we need to get this done," he said.
"And what I confess I did not expect -- and so I'm happy to take responsibility for being naive here -- is that Republicans who had previously supported comprehensive immigration reform -- my opponent in 2008, who had been a champion of it and who attended these meetings -- suddenly would walk away," Obama said. "That's what I did not anticipate. …
"Well, Jorge, as you remind me, my biggest failure so far is we haven't gotten comprehensive immigration reform done," the president said, drawing a laugh from the audience. "So we're going to be continuing to work on that. But it's not for lack of trying or desire, and I'm confident we're going to accomplish that."
Asked about a statement by the White House press secretary that the attack in Benghazi, Libya, in which U.S. Ambassador Christopher Stevens and three other Americans were killed was a terrorist attack, Obama said the matter was still being investigated "so I don't want to speak to something until we have all the information."
He said investigators do not know yet whether the attack was carried out by al-Qaida.
In response to controversial remarks by Republican nominee Mitt Romney about Americans who pay no federal income taxes, the president said, "When you express an attitude that half the country considers itself victims, that somehow they want to be dependent on government, my thinking is maybe you haven't gotten around a lot, because I travel around the country all the time and the American people are the hardest working there are.
"Are there people who abuse the system? Yes, both at the bottom and at the top -- because there are a whole bunch of millionaires who aren't paying taxes at all either," he said.