WASHINGTON -- After billions of dollars, hours of debates and frantic last-minute pitches from the candidates, it's up to the voters Tuesday to decide whether to give U.S. President Barack Obama a second term or change course with Republican Mitt Romney.
Also at stake is control of Congress. Thirty-three Senate seats and all 435 House of Representatives seats are up this year, and while the House is expected to remain in Republican hands, Senate control hinges on a host of tight races.
Turnout will be one key to handicapping who's winning the White House and congressional battles, heading a long list of unknowns. Will the relentlessly negative campaign help or hurt? Did superstorm Sandy benefit the president? Did early voting give him a big advantage?
Once the polls close starting at 6 p.m. EST in Indiana and Kentucky, a number of early clues will signal whether Obama or Romney will get the 270 electoral votes needed to win. Polls on Monday continued to show the race a virtual tie nationally and in most of the 11 battleground states.
The first hints of how the night might go will come in four early poll-closing states: Virginia, North Carolina, New Hampshire and Indiana. Obama won all four in 2008.
Romney needs all four if he's to become the sixth person in 100 years to defeat a sitting president. Should he falter in even one, or the results become too close to call, this race won't be over quickly.
Obama, on the other hand, can score an important win early by taking Florida. Losing its 29 electoral votes would be a huge blow to Romney, who has pushed hard for the state's votes and began his last full campaign day Monday in Orlando.
"Tomorrow we begin a better tomorrow," Romney told about 1,000 supporters, stressing his closing argument that Obama bungled the economy and is too fierce a partisan to work with Republicans.
The president was in Madison, Wis., where he appeared with legendary rocker Bruce Springsteen.
"I stood with President Obama four years ago, and I'm proud to stand with him today," Springsteen said. Obama hugged the singer and reminded the crowd, "We've got more change to make."
Turnout was expected to be down somewhat from 2004 and 2008, according to models developed by the Gallup Organization. Voters "have not been quite as engaged" in the election, a Gallup analysis said, and many voters could be distracted by Sandy, whose impact is still being felt in parts of the Northeast.
As the night unfolds, here's how to watch the returns:
Most states are solidly for Obama or Romney, so 11 are likely to decide the race. All have polling places scheduled to close by 10 p.m. EST. All went for Obama last time, and he has to hold onto most of them to win again.
Hour by hour
6 p.m.: Virginia. Obama's 2008 victory was the first there by a Democratic presidential candidate since 1964. Romney needs its 13 electoral votes.
6:30 p.m.: Ohio, North Carolina. Romney needs Ohio and its 18 electoral votes; no Republican has won the White House without the state. North Carolina is another state Obama won in 2008, the first time a Democrat had taken it in decades, but Romney is counting on winning its 15 electoral votes. If not, he's probably in trouble.
7 p.m.: New Hampshire, Florida, Pennsylvania. If Obama wins Florida, Romney's chances would get shakier. But if Romney wins Pennsylvania's 20 electoral votes, which Obama has regarded for months as his, the president should start worrying. The four electoral votes of New Hampshire -- Democratic in the last two elections -- matter if the race stays close.
8 p.m.: Wisconsin, Colorado, Michigan. A Romney win in Michigan -- a state Obama won last time by 16 percentage points -- would be another sign that the president is faltering. Wisconsin and Colorado are toss-ups.
9 p.m.: Iowa, Nevada. Nevada has been trending Democratic. A strong Latino turnout would be a signal that Obama is doing well. Iowa is another toss-up.
Turnout: Conventional wisdom says Democrats tend to dominate early voting, while Republicans do better on election day, so a big turnout could mean a big day for Romney.
Latino voting: Tuesday marks the culmination of four years of registering new voters in hopes of harnessing growing Latino clout and finally shattering the reputation that Latinos are apathetic voters who can be ignored. In 2008, 50 per cent of eligible Latino voters cast ballots, compared with 65 per cent of blacks and 66 per cent of whites, according to the Pew Hispanic Center.
The National Association of Latino Elected and Appointed Officials estimates 12 million Latino voters will visit the polls in this year's election, which would be a 26 per cent increase from 2008. More than three million Latinos are expected to vote in their first presidential election. A big turnout could mean the difference in Colorado, Nevada and perhaps Arizona.
Long lines: Polls might stay open past closing time, delaying the vote count. But if lines are too long and people get discouraged, they might go home.
Hurricane Sandy: Will voters be more sympathetic to Obama in hard-hit states such as Pennsylvania or New Hampshire? Or blame the feds for being too slow to respond?
Romney plans to vote early Tuesday at a Belmont, Mass., polling place near his home. Obama voted last month. Once the results are in, the president plans to address a rally at Chicago's McCormick Place. Romney will host supporters at the Boston Convention and Exhibition Center.
One of the night's most unpredictable cliffhangers involves control of the Senate.
Democrats now control 53 of the 100 seats, and they're defending 23 to the Republicans' 10. Close races in Virginia, Indiana and Massachusetts might offer early hints as to whether Republicans can achieve the net gain of four -- three, if Romney is elected -- to win control.
The next group of close races is farther west, notably in Wisconsin, Montana, Nevada and Arizona.
In the House, Democrats need a net gain of 25 for control, but independent analysts don't expect the party to gain more than 10.
In most areas, full election coverage begins at 5 p.m. on CNN and MSNBC, at 6 p.m. on ABC, Fox, CBS, NBC and Univision, and at 7 p.m. on PBS.
-- McClatchy Newspapers