More than 27 million ballots have been cast in 34 states and the District of Columbia, although none will be counted until Election Day on Tuesday.
Nearly 4 million of them were deposited by Floridians, and Democrats cited unprecedented demand for pre-election day voting as they 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 on Saturday in a bomb scare.
Obama and Romney disagree sharply about the approach the nation should take to the slow-growth economy and high unemployment, and the differences have helped define the campaign. Most notably, Romney wants to extend tax cuts that are due to expire without exception, while Obama wants to allow them to lapse on incomes over $250,000.
At the same time, polls show bipartisanship is popular, in the abstract, at least, which accounts for the emphasis the candidates are placing in the race's final days on working across political aisles.
Romney frequently cites his ability to work with the Democratic-controlled Legislature while he was governor of Massachusetts, although he rarely mentions the veto battles he had.
Obama's term has been littered with the legislative wreckage left behind by constant struggles with congressional Republicans. Yet his trip to New Jersey last Wednesday was a model of nonpartisanship as he accompanied Republican Gov. Chris Christie on a tour of destruction caused by Superstorm Sandy. The governor repeatedly praised the administration's response to the storm.
One prominent Republican said the storm had worked to Romney's disadvantage in a different way.
"The hurricane is what broke Romney's momentum. I don't think there's any question about it," former Mississippi Gov. Haley Barbour said on CNN's "State of the Union."
"Any day that the news media is not talking about jobs and the economy, taxes and spending, deficit and debt, Obamacare and energy, is a good day for Barack Obama," he said. "Now, whether it will be good enough remains to be seen."
Romney's campaign wanted no part of that. "I don't look at what happened with the storm and how it affected so many people through a political lens," said a spokesman, Kevin Madden.
So intense was the campaigning that Vice President Joe Biden's plane and the one carrying Romney were both on the tarmac in Cleveland at the same time in early afternoon. The two men did not see one another.
Biden's assignment for the day was to rally voters across Ohio. "These guys are trying to play a con game here at the end," he said of Romney and Ryan, whom he accused of posing as more moderate than they are.
Ryan started out in his home state of Wisconsin. He donned a Green Bay Packers jacket and a yellow and green striped tie for a pregame tailgating party he attended briefly across the street from fabled Lambeau Field.
Then, football or no football, it was off to Ohio, Minnesota and Colorado.
Espo reported from Washington. Associated Press writers Steve Peoples and Kasie Hunt in Pennsylvania; Matthew Daly in Ohio; Phil Elliott in Wisconsin; and Beth Fouhy and Josh Lederman in Washington contributed to this report.