(Newsroom America) -- More than one in five swing-state voters are either undecided or say there is at least a slight chance they may change their vote preference between now and the election, according to a new USA Today/Gallup poll.
The results are based on a Sept. 11-17 USA Today/Gallup Swing States poll of 1,096 registered voters in Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin.
Registered voters in the swing states remain closely divided in their presidential vote preferences, according to the poll, with 48% supporting President Barack Obama and 46% Mitt Romney.
The poll found 22% of swing-state voters are either undecided (5%) or say there is at least a slight chance (17%) they may change their vote preference between now and the election.
That 22% of swing-state voters includes 10% who currently support Obama and 7% who now prefer Romney.
Obama won all 12 swing states in 2008 and Gallup said Romney would need to win roughly two-thirds of the available 151 electoral votes in the swing states to be elected.
Gallup Daily tracking of registered voters nationwide now finds Obama at 47% and Romney at 46%.
Gallup said it was too early to tell what if any impact a newly released video of Romney's unflattering characterization of Obama supporters from a May fundraising speech might have on the race.
Gallup said it had 95% confidence that the maximum margin of sampling error is ±4 percentage points.