After months of campaigning, countless political ads and an estimated $4 billion spent by the candidates and their backers, Americans are taking to the polls to deliver the final verdict on a host of races and issues.
The control of Congress will come down to two key numbers - 10 and 39. For a majority in the Senate, Republicans need to pick up an additional 10 seats. In the House of Representatives, the magic number is 39.
It's a near certainty the GOP will be able to hit that goal in the House. The only question is whether they can pick up a win of epic proportion, wresting 60 or more seats from their Democratic foes, reports CBS News correspondent Nancy Cordes.
"If we're lucky enough to be in the majority and I'm lucky enough to be speaker of the house, it's gonna be real different," Rep. John Boehner, R-Ohio, told cheering supporters.
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John Boehner and his fellow Republicans have every reason to be cheering. According the latest Gallup poll, an unprecedented 55 percent of likely voters say they'll be casting their ballot for the GOP, compared to just 40 percent for the Democrats.
The last time Republicans did so well was in 1994 - the year of the Republican revolution when they picked up 52 seats. Projections forecast similar gains tonight.
In a last minute scramble for votes, Democrats brought out their biggest starts.
"Everybody is playing politics and they are trying to turn three-dimensional people into two-dimensional cartoons," former President Bill Clinton said Monday in West Virginia, where he was rallying support for Democratic Senate hopeful Gov. Joe Manchin.
In Nevada, First Lady Michelle Obama campaigned for Senate Majority Leader Harry Reid, who is fighting for his political life against Tea Party-supported Sharron Angle. Most polls show he's trailing.
President Barack Obama has stayed out of sight after a weekend of last-ditch campaigning, giving radio interviews and filming a get-out-the-vote ad for AOL.
Here's a snapshot of what's at stake in the election:
On Election Day, 37 Senate seats are up for election, 19 held by Democrats and 18 by Republicans. Fourteen of these seats are open - six Democratic and eight Republican - meaning there is no incumbent competing in the election.
Three of the races are open because the incumbent lost his or her party nomination, either in the primary or state convention: Republican Sen. Bob Bennett of Utah; Republican Sen. Lisa Murkowski of Alaska; and Democratic Sen. Arlen Specter of Pennsylvania. Murkowski is running as a write-in candidate.
The party breakdown in the Senate is 57 Democrats, 41 Republicans and two independents who caucus with the Democrats.
All 435 House seats are at stake. A party must win 218 seats to get a majority.
The party breakdown in the House is 255 Democrats, 178 Republicans and two vacancies.
Four House incumbents lost their primary elections: Democratic Rep. Alan Mollohan of West Virginia, Republican Rep. Parker Griffith of Alabama; Republican Rep. Bob Inglis of South Carolina, and Democratic Rep. Carolyn Cheeks Kilpatrick of Michigan.
Thirty-seven state governorships are up for election. Of these 19 are held by Democrats and 18 by Republicans. Twenty-four are open - 12 Democratic and 12 Republican.
Fifteen of the races are open because the incumbent is barred from running again by term limitations. One race is open because the incumbent, Gov. Jim Gibbons, a Nevada Republican, lost his primary race.
The party breakdown on governorships is 26 Democrats and 24 Republicans.
A total of 6,115 out of 7,382 state legislative seats are up for election in 46 states.
Currently 27 state governments are controlled by Democrats and 14 by Republicans. Eight state governments are divided between the two parties. One state, Nebraska, has a nonpartisan legislature.
One hundred sixty ballot questions will be decided in 37 states. Of these, 42 were initiated by citizens.
One of the most well-known ballot measures is the California initiative to legalize recreational use of marijuana. Three other states will also tackle this issue to different degrees. Arizona and South Dakota will both vote on the legalization of using marijuana for medical purposes. A measure in Oregon would establish a medical marijuana supply system and allow limited sales of marijuana.
In Colorado, the ballot will include a proposed amendment that would define a person in the state's bill of rights from the beginning of "biological development," potentially laying the framework for outlawing abortion in Colorado.
Arizona, Colorado and Oklahoma have proposed amendments aimed at taking down the segment of the new federal health care law that will require people to have health insurance.