U.S. President Barack Obama has expanded his lead over Republican rival Mitt Romney in the race for the White House by as much as 12 percent in three critical “battleground” states, according to a new poll of likely voters released Wednesday.

"Gov. Mitt Romney had a bad week in the media and it shows in these key swing states," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute. The survey was conducted September 18 to 24 by Quinnipiac University, CBS News and The New York Times.

The poll puts Obama ahead of Romney by 53-44 percent in Florida, 53-43 percent in Ohio, and 54-42 percent in Pennsylvania. Since 1960, no one has been elected to the White House without winning at least two of the three.

Around 1,200 likely voters in each of the three states were surveyed, and the poll has a margin of error up to 2.9 percent. Poll respondents in all three states found Obama better able to handle critical issues including the economy, health care and an international crisis. Romney, they found, was better able to handle the budget crisis.

The two men begin a series of debates next month, which may be Romney’s best chance to reverse the trend in his favor, say pollsters. Both candidates campaigned in Ohio on Wednesday.