Quinnipiac University released polls for Florida, Ohio and Pennsylvania, all states that could prove decisive in the election.
Florida remains the tightest of the critical trio of states, with a 47-45 edge for Obama, according to the Quinnipiac poll.
Ohio appears to be tilting toward Obama with a 50-43 lead, and Obama appeared to have a comfortable 52-42 lead in Pennsylvania, also according to Quinnipiac.
Both candidates have mapped out punishing schedules for themselves on the final day of campaigning, to generate a big turnout among their supporters and to convince the few voters yet to make up their minds to pull the lever that bears their name.
More than 25 percent of the nation's voters have already cast their ballots, and 7 percent of the vote remains up for grabs, according to the ABC News/Washington Post poll.
The importance of those states is seen in the dueling campaign schedules.
Both Obama and McCain start their final drives in Florida, the state that settled the 2000 election. And their vice presidential contenders Biden and Alaska Gov. Sarah Palin will appear in Ohio, the state the nailed the 2004 election for President Bush. Both campaigns will also make stops in Pennsylvania.
Obama, his wife, Michelle, and his running mate will spread out to stump in North Carolina, Missouri, Nevada, Colorado, Virginia, Indiana, Delaware and Illinois. Obama will continue campaiging on election day in Indiana.
McCain and Palin will touch down in many of the same states. Their hopscotch itinerary includes Tennessee, Indiana, New Mexico, Iowa, Nevada, Colorado, Arizona and Alaska.
McCain will keep campaigning through Election Day.
After voting in Arizona Tuesday morning, he will jet off for get-out-the-vote appearances in New Mexico and Colorado.
McCain and Obama will also get their last shot at a national audience by appearing during half time tonight on "Monday Night Football."
Obama's camp is taking care not to sound over confident.
Caroline Kennedy, an early Obama supporter, told "Good Morning America," "I'm always worried. ... If everyone gets out there we'll be OK."
McCain supporter Mitt Romney, a rival to McCain for the Republican presidential nomination who has been campaigning for the GOP candidate, was more bullish.
"I expected to find people discouraged," he told 'GMA'. "They're enthusiastic. They expect to win. ... For Obama and the million or so people who expect to be with him in Chicago [on election night] it could be a long cold night."
McCain was encouraged by a midnight rally in Miami Sunday night that drew 10,000 supporters.
"We've got to have all of our rallies at this time of night, I'm telling ya," McCain said enthusiastically.
"This is the kind of intensity, this is the momentum, that we will win Florida, and we will win this election," McCain said.
But McCain's path to the White House appears more complicated at this point.
The undecided voters are composed primarily of women, the elderly and the economically distressed, ABC News' chief Washington correspondent George Stephanopoulos explained on "GMA."