SANFORD, Fla. — President Barack Obama and Republican Mitt Romney made their last stands of the 2012 campaign Monday, employing their last vestiges of energy, celebrity boosters and plenty of jet fuel to encourage every supporter and the few remaining undecideds to tip the vote in their favor.

National polls of the eve of Election Day showed a neck-and-neck race. But the winner will be determined by which man gets 270 electoral votes, and Obama had more paths to get there.

The incumbent and the challenger, both fighting weariness and speaking in voices that have turned hoarse, closed by arguing they could do more to lead the country out of the tough economic times that dominated Obama's term. "This nation is going to begin to change for the better tomorrow," Romney said.

"Our work is not yet done," Obama told nearly 20,000 people who filled the street in front of the Wisconsin capital building.

Both men campaigned in states they need to win. Romney was in Florida, Virginia, and New Hampshire, while Obama was trying to protect Wisconsin from a late-breaking GOP challenge before heading to Iowa.

And in an indication of just how all-important Ohio was once again to the future occupancy of the White House, both candidates planned to be on the ground in Columbus in the evening for dueling rallies several hours and seven miles apart. The state has gone for the winner in every presidential election since 1964.

Republican campaign officials said Romney was considering a possible return to Ohio on Tuesday. Without the state, he has to win nearly every other battleground state to defeat Obama.

Both candidates were also hoping to benefit from some star power. Romney planned a final rally in the day's final hour in New Hampshire with Kid Rock while country rock performers The Marshall Tucker Band was joining him in Columbus. Obama had actors Samuel L. Jackson and Chris Rock doing urban radio interviews, "Mad Men" star Jon Hamm making calls in Colorado, rapper Jay-Z joining him in Columbus and rock legend Bruce Springsteen as his traveling warm-up act.

"He promised me a ride on Air Force One," Springsteen said, strumming his guitar as he made a political pitch between songs.

The rivals planned to appeal to pro football fans in the eleventh hour, taping interviews with ESPN's Chris Berman that will air during halftime of the Monday Night Football game between the Philadelphia Eagles and the New Orleans Saints.

Both candidates predicted the winner will be determined by which of their operations can get the most supporters to the polls. "This is going to be a turnout election," the president declared in an interview broadcast early Monday as he pleaded with urban radio listeners to get to the polls.

Romney's rally in Lynchburg, Va., featured an enormous "Get Out and Vote" banner. "We have one job left," and that's getting people out to vote, Romney told more than a thousand people at a rally at his previous stop, the airport in Sanford, Fla., near Orlando. The crowd chanted "One more day!"

Obama raised the possibility of defeat as he pleaded with listeners of The Rickey Smiley Morning Show to get to the polls. "If we don't turn out the vote, we could lose a lot of the gains we've already made," Obama said.

It was one of two of the president's radio interviews airing Monday aimed at turning out minority voters, the other with a Spanish-language station in Ohio. The president is relying on black and Hispanic voters to help offset Romney's lead with white men in particular, but the risk for him is that some of those key supporters aren't as motivated to vote as they were in 2008.

"Four years ago, we had incredible turnout and I know people were excited and energized about the prospect of making history," Obama said. "We have to preserve the gains we've made and keep moving forward."

A final national NBC/Wall Street Journal Poll showed Obama getting the support of 48 percent of likely voters, with Romney receiving 47 percent. A Washington Post-ABC News tracking poll had Obama at 49 and Romney at 48. A Pew Research Center poll released Sunday showed Obama with a 3-point-point edge over Romney, 48 percent to 45 percent among likely voters.

Obama dispatched former President Bill Clinton to Pennsylvania on Monday to keep the state in his column. First lady Michelle Obama went south to North Carolina and Florida. Vice President Joe Biden made a final reach in Virginia, while Romney running mate Paul Ryan was covering the most ground, flying to Nevada, Colorado, Iowa, Virginia and Wisconsin.

Meanwhile, about 30 million people have already voted in 34 states and the District of Columbia, either by mail or in person, although no ballots will be counted until Election Day, Tuesday. More than 4 million of the ballots were cast in Florida, where Democrats filed a lawsuit demanding an extension of available time. A judge granted their request in one county where an early voting site was shut down for several hours Saturday because of a bomb scare.

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Pickler reported from Washington. Associated Press writers Jim Kuhnhenn and Stephen Ohlemacher in Washington, Julie Pace in Madison, Wis., and Steve Peoples in Sanford, Fla., contributed to this report.