1 debate left; 2 alphas, President Barack Obama and Mitt Romney, wage fight of their lives

The candidates were in each other's faces — sometimes literally — before an audience of 82 uncommitted voters from New York. It's a state that's already a sure bet for Obama, but the voters there stood as proxy for millions of Americans across the nation still settling on a candidate.

"They spent a lot of time cutting down the other person," said 22-year-old Joe Blizzard, who watched with a crowd of 500 students at the University of Cincinnati. "As someone who is undecided, it was a little disappointing."

Fellow student Karim Aladmi, 21, was more forgiving. "It goes without saying that the knives were out," he said. "I thought Obama had a strong performance, but Romney made him work for it. I was actually impressed by both sides."

With just 20 days left until the election, polls show an extremely tight race nationally. While Republicans have made clear gains in recent days, the president leads in several polls of Wisconsin and Ohio. No Republican has won the White House without winning Ohio.

In the sprint to Election Day, every aspect of the campaign seems to be taking on a fresh sense of urgency — the ads, the fundraising, the grass-roots mobilizing, the outreach to key voting blocs, particularly women.

Both sides are pouring millions upon millions into TV ads in the battleground states, and independent groups are adding buckets more.

The debate didn't break a lot of new ground, although Romney signaled a shift in his stance on immigration.

The GOP nominee previously had said he would veto legislation to provide a path to legalization for young illegal immigrants brought to the United States as children. But Tuesday night, he said such young people "should have a pathway to become a permanent resident of the United States."

As the debates unfold, early voting is already under way in many states, and the push to bank as many early ballots as possible is in overdrive.

Democrats cheered when the Supreme Court on Tuesday cleared the way for Ohio voters to cast ballots on the three days before Election Day, rejecting a request by the state's Republican elections chief and attorney general to get involved in a rancorous battle over early voting. Obama's campaign and Ohio Democrats had sued state officials over changes in state law that took away the three days of voting for most people.

All of the political maneuvering was little more than noise for more than 1.3 million Americans: They've already voted.

Benac reported from Washington. AP writers Nedra Pickler and Alicia Caldwell in Washington, James Fitzgerald and Steve Peoples in Hempstead, N.Y., and Dan Sewell in Cincinnati, Ohio, contributed to this report.

Follow Nancy Benac on Twitter: http://www.twitter.com/nbenac

Follow Julie Pace on Twitter at http://twitter.com/jpaceDC