Private polling from both parties has Obama leading Romney in Ohio, where the president's bailout of the auto industry is popular. And more Democrats than Republicans in the state have cast early votes.
Romney's campaign is looking to expand the battleground map by making a late play for a trio of left-leaning states: Pennsylvania, Michigan and Minnesota. That's forced Obama's team to buy television advertising time in states where it had hoped to avoid spending money.
Obama aides insist it's not in trouble in those states and aides say there are no plans for Obama or Vice President Joe Biden to travel there in the campaign's closing days. Instead, they say their strong fundraising efforts have given them the financial means to defend against Romney's criticism wherever he decides to run ads.
But aides say turnout, not ads, will determine the election. Obama's team has put particular emphasis on ramping up turnout during early voting periods, especially among "sporadic" voters who may be less likely to go to the polls on Election Day.
Their efforts appear to be bearing fruit. Democrats have an edge in votes cast in Florida, Iowa, Nevada, North Carolina and Ohio. Republicans have an advantage in Colorado.
Obama's campaign says boosting early vote totals could put some states out of reach for Romney even before Election Day. In Ohio, for example, Obama aides estimate the Republican would need to carry at least 53 percent of the vote cast there on Tuesday in order to remain in contention.
It's more than just party registration that has Obama's team feeling confident. They tout data showing two-thirds of those who have already voted were women, young people, blacks and Hispanics. Obama is almost certain to win the majority of those voting blocs.
Aides say minority voting in particular is on track to reach an all-time high, perhaps as high as 28 percent of all voters.
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