After campaigning for almost two years, the candidates were running on adrenaline and buoyed by big crowds and preparing to end up in their home states—Obama in Illinois, McCain in Arizona—to await Americans' judgment Tuesday.
Huge challenges are in store for the winner, including restoring growth to the sagging U.S. economy, fighting wars in Iraq and Afghanistan, getting a handle on a budget deficit running close to $500 billion and restoring the luster of the world's lone superpower.
Interest in the election to determine a successor to unpopular President Bush was high. Millions of Americans had already voted early and election officials were bracing for long lines at polling stations. A record turnout, easily eclipsing the 2004 vote total of more than 121 million, was possible.
The candidates began the last day of campaign 2008 in Florida, scene of the famous 2000 recount battle that Bush won and a state McCain needs to stave off defeat.
Illinois Sen. Obama, 47, who would be America's first black president, rode his message as an anti-Bush change agent and was sailing along with the lead in national opinion polls and in many swing states that will determine the outcome.
Obama, who was also campaigning in North Carolina and Virginia, said in Jacksonville: "I have just one word for you, Florida: Tomorrow."
"In these last 36 hours, we can't afford to slow down or sit back or let up, not one minute, not one hour, not one second. Not anytime in the next thirty six hours," he said.
He said McCain could point to a few instances where he broke with Bush but "when it comes to the economy, when it comes to the central issue of this election, the plain truth is that John McCain has stood with George Bush every step of the way."
'Measuring the Drapes'
"The pundits have written us off just like they've done before and my opponent is measuring the drapes in the White House," McCain told a spirited rally in Tampa, Florida. "The pundits may not know it and the Democrats may not know it, but 'the Mac' is back. We're going to win this election."
McCain, 72, who would be the oldest person ever elected to a first presidential term, accused Obama of wanting to raise taxes to pursue liberal policies.
"He's in the far left lane of American politics and he's stuck there," McCain said in Blountville, Tennessee. He had stops planned in Pennsylvania, Indiana and New Mexico as well.
The two-year campaign, which has been estimated to cost $2 billion, will extend even into Election Day. McCain will make stops in Colorado and New Mexico after voting in Arizona.
Obama will make a final plea for votes Tuesday in Indianapolis. Usually a solid Republican state, Indiana is flirting with Obama this year.
Americans will vote in what amounts to 51 separate elections in each state and the District of Columbia. Each state is allocated electoral votes based on the size of its representation in Congress. Whoever gets 270 electoral votes wins the White House.
While Obama has many combinations of states that he can use to get to 270, McCain's path is narrow. He has been mostly racing around states Bush won in 2004 trying to defend them while hoping to nab traditionally Democratic Pennsylvania.
In Congressional elections Tuesday, Democrats appeared poised to make gains in their majorities in both the U.S. House of Representatives and the Senate. All 435 House seats are at stake and 35 of the Senate's 100 seats are up for election.
