Aiming to seal the victory and become the nation's first black president, Obama raced into a day that would take him from to to , all traditionally Republican territory.
McCain rolled by bus through battleground five days before the election, struggling to make up ground in a state that has voted with the winner in every presidential election for two decades.
By all available evidence, on the Thursday before Election Day the race was Obama's to lose.
The national polls showed him ahead, he was rated the favorite in a half-dozen states that sided with Mr. Bush in 2004, and surveys showed close races in three more.
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Both campaigns invested heavily in turning out early voters.
Officials in said roughly 30 percent of all registered voters had already cast ballots - about 1.7 million in all - and the Board of Elections ordered the state's 100 counties to keep longer voting hours.
Like the opinion polls, the early ballot count favored Obama. Officials in , , , and as well as said more Democrats that Republicans had cast ballots, in some cases by lopsided margins.
Democrats, increasingly optimistic about regaining the White House, looked forward to padding their majorities in Congress, too, and then tackling the economy and bringing the war in Iraq to an end.
But McCain and his aides sought to stoke doubts about one-party government. The campaign challenged Obama to say whether he supports a 25 percent cut in defense spending that is advocated by some in his party
In Sarasota, his first stop of the day, Obama tried to take advantage of the day's dreary business news, a government report that consumers cut back spending so sharply that the economy had shrunk at an annual rate of 0.3 percent in the third quarter.
It was the economy's worst showing since the fall of 2001, when a recession in progress was compounded by the impacts of the terrorist attacks of Sept. 11.
"Folks have to watch every penny, tighten their belts," said Obama, contending that the downturn was the result of eight years of Republican economic policies.
"If you want to know where John McCain will drive this economy, just look in the rearview mirror. Because when it comes to our economic policies, John McCain has been right next to George Bush. He's been sitting there in the passenger seat, ready to take over, every step of the way," he added.
Obama's campaign re-enforced the rhetoric with a new television commercial. It showed the faces of Bush and McCain together in a car's rearview mirror as the announcer said, "Look behind you. We can't afford more of the same."
In a second ad, Obama touted endorsements from Colin Powell, the former secretary of state and chairman of the Joint Chiefs of Staff, and Warren Buffett, arguably the nation's best known investor. (Read more about the ads)
Those ads followed up Obama's 30-minute infomercial that aired on multiple channels Wednesday night at a cost of $4 million. ( )
Nielsen ratings that were released on Thursday showed that the ad was watched by 33.5 million people on CBS, NBC, Fox, Univision, MSNBC, BET and TV One.
In the 30-minute primetime campaign ad, Obama promised a rescue plan for the middle class in tough times as he reached for victory in his 21-month quest for the presidency.
"I will not be a perfect president," Obama said in the commercial. "But I can promise you this - I will always tell you what I think and where I stand."
As for reaction, CBS News senior political correspondent Jeff Greenfield said he doubts the ad changed many minds, but the goal of it was just to increase the "comfort level between Obama and voters."
"The spin doctors who put together this infomercial followed their own version of the Hippocratic Oath: 'first, do no harm.' It was an exercise in reassurance, from the reassuring images -- amber waves of grain, anyone -- to the soothing music, to Obama's low-pitched voice, to the stories of his childhood and his family, to his narrations of the lives of typical Americans," Greenfield said. "This was all one message: 'I may have an odd name, come from a big city, and I'm obviously of a different color than other presidents -- but I share common roots, common values, and I understand what you are going through, and what you need from your government.'"
McCain's first stop of the day was in chilly Defiance, Ohio, where he did not dwell on the economic report. Instead, he pointed to Exxon Mobil's announcement of a $14.83 billion profit in the third quarter, a record, and said Obama had voted for legislation that included millions in tax breaks for oil companies.
"Senator Obama voted four billions in corporate giveaways to the oil companies," said McCain in an apparent reference to a 2005 energy bill that Bush pushed through Congress.
"I voted against it," the Arizona Republican said.
The legislation included nearly $3 billion in tax breaks for the oil and natural gas industry including some - but not all - that would benefit the largest oil producers such as Exxon Mobil Corp. It also had $11.4 billion in tax incentives for alternative energy and efficiency programs, cited by Obama as his reason for supporting the legislation.
Meanwhile, McCain's running mate, Alaska Gov. , says there is nothing wrong with calling out Obama on his past associations or other controversial elements of his record. Besides Obama's association with '60s-era radical Bill Ayers - Palin has accused Obama of "palling around with terrorists" - both McCain and Palin have now brought up Obama's friendship with a Palestinian-American professor, Rashid Khalidi, who has been critical of Israel.
Asked by ABC if she was suggesting in any of her criticism that Obama is un-American, Palin said: "No, not at all. Not calling him un-American." She added, "I am sure that Sen. Obama cares as much for this country as McCain does."