FAIRFAX, Virginia Presidential elections typically end with a flurry of late rallies, as candidates hopscotch across the country to make last-minute appeals, in person, to as many voters as possible.
But there is little evidence to show that the frenzied late campaigning pays off - especially this year, when millions of Americans have already cast their ballots for President Barack Obama or Republican challenger Mitt Romney well before Election Day on Tuesday.
"They've never mattered less," said Jeremy Mayer, a political scientist at George Mason University in Fairfax, Virginia, where Romney held one of five rallies on Monday.
"Early voting really takes away the importance of getting out the vote," Mayer said.
Obama was on a campaign schedule similar to Romney's. Between them, the two candidates will have held dozens of rallies - drawing hundreds of thousands of voters - in the last few days of campaigning.
Their days start before dawn and end well after midnight. They fly across the country with an army of staffers, press and security, shored up by hundreds of millions of dollars in advertising.
Still there is little chance that either candidate would opt out of the frenetic last-minute schedule. Romney's campaign even added another last-minute trip - on Election Day - to the swing state of Ohio as well as to Pennsylvania, where the Republican has seen his poll numbers surge in recent weeks.
Polls show the race for the presidency is too close to call and campaign strategists are convinced the last-minute rallies are worth it, saying that late rallies could determine the victor, even if they draw only a couple of thousand new supporters.
"We go where the votes are," a Romney aide told reporters.
Besides, noted Mayer, neither Obama nor Romney wants to end up like candidates who have lost close elections in the past.
In 1976, Republican President Gerald Ford lost to Democratic challenger Jimmy Carter after his campaign decided not to campaign hard in New York. If Ford had pushed there, he might have won the 1976 election.
Or in 2000, Vice President Al Gore lost the electoral vote to Republican George W. Bush because of a few hundred votes in Florida. And in 2004, Democratic challenger John Kerry lost the White House race because of a few thousand votes in Ohio.
Mayer said candidates campaign right up until the last moment because they do not want to risk defeat without making one final effort.
"At the individual level, to avoid incredible feelings of remorse from now to the grave, both of these men are going to go all out. Because what else are they going to do?" Mayer said.
"The remorse of the close election loser is so great that you'd do almost anything to avoid it."
(Reporting By Patricia Zengerle; editing by Alistair Bell and Christopher Wilson)