He cited the DREAM Act -- the legislative predecessor to last Friday's DHS announcement -- and noted that Romney had vowed to veto that bill. 

"He has promised to veto the DREAM Act, and we should take him at his word," Obama said. "I believe that would be a tragic mistake." 

Obama criticized lawmakers for not passing that proposal, claiming his administration took action because Congress wouldn't. "The bill hadn't changed. The need hadn't changed. The only thing that had changed was politics," he said. 

The forum in Florida was just the latest stage where Obama and Romney have waged their budding general election battle. 

Romney, a day earlier, accused Obama of pandering to America's Latinos with the Department of Homeland Security announcement and urged the Latino community to consider an "alternative" in the November election. Obama, he said, is "taking your vote for granted."