The USC Dornsife/Los Angeles Times poll shows Obama leading Republican nominee Mitt Romney by 14 percentage points, the Times said. Obama was 24 points ahead of U.S. Sen. John McCain, R-Ariz., in 2008.
Obama received the votes of many disaffected Republicans four years ago but they have since moved away from supporting him, the Times said.
He now leads among white men by a single point, in contrast to 14 points four years ago.
Mike Denny of Rossmoor, a Republican, voted for Obama in 2008.
But he says Obama's healthcare plan will hurt small businesses like his graphics company.
"I thought maybe there would be some kind of change," Denny said. "I thought he was somebody different, someone new with new ideas, someone with young ideas. But it's the same old thing."
The poll was conducted by two polling companies, the Democratic Greenberg Quinlan Rosner and the Republican American Viewpoint. Pollsters interviewed 1,504 registered voters by phone between Oct. 15 and 21. The margin of error is 2.9 percentage points.