The US presidential rivals are spending a hectic final day of campaigning criss-crossing the country in a last push for votes in key states.
Republican John McCain, trailing in polls, started early in Florida and is to finish close to midnight in Nevada, more than 1,800 miles (3,000km) west.

Democrat Barack Obama opted to target Florida, North Carolina and Virginia - all won by the Republicans in 2004.
On Tuesday, voters give their verdict and elect the 44th US president.
On the eve of the ballot, Republican vice-presidential candidate Sarah Palin was cleared by an investigator of abusing her power as governor of Alaska.
The report for the Alaska Personnel Board found that there was "no probable cause to believe that the governor, or any other state official" violated state ethics laws.
An earlier investigation for Alaska's state legislature had found Mrs Palin did abuse her office by allowing her husband and staff members to pressure Alaska's top law enforcement official to fire her former brother-in-law.
Mrs Palin fired Walt Monegan, the state public safety commissioner, but denied it was because of his refusal to dismiss her sister's ex-husband, a state trooper.
Tributes to grandmother
Meanwhile, Senator Obama said his grandmother, Madelyn Dunham - who largely raised him as a child - had died aged 86 in Hawaii after losing her battle with cancer.
Barack Obama pays tribute to his grandmother
In a joint statement with his half-sister, he described her as "the cornerstone of our family, and a woman of extraordinary accomplishment, strength, and humility", adding that their debt to her was "beyond measure".
Senator McCain and his wife Cindy issued a statement offering their deepest condolences to Mr Obama and his family.
Two weeks ago, Mr Obama took the unusual step of breaking off campaigning for two days to visit his grandmother, saying he did not want to risk leaving it too late to see her.
A USA Today/Gallup poll published on Monday finds likely voters favouring Mr Obama by 11 points over Mr McCain, 53-42%.