Race comes down to Ohio as Obama nabs six key states

Supporters of U.S. President Barack Obama cheer during the Obama Election Night watch party at McCormick Place. …

Polling places have closed in all but a few states, bringing America that much closer to knowing whether Mitt Romney or President Barack Obama will be in the White House come January.

After countless stump speeches, three debates and historic levels of advertising—it's estimated that $2.6 billion was spent in the presidential race—tens of millions of Americans, some of whom had to stand in line for hours, cast their ballots. Tonight's winner will most likely inherit at least one crucial Supreme Court nomination, plus messy Congressional negotiations about whether to let the Bush tax cuts expire, and an unpopular 10-year war in Afghanistan.

Polls in 40 states have already closed, including the polls in all but two crucial swing states. ABC News has projected that Romney will win 18 red states, while Obama will carry 13 states and Washington D.C. So far, networks have called six crucial swing states--Michigan, New Mexico, New Hampshire, Minnesota, Wisconsin and Pennsylvania--for Obama. Romney picked up the swing state of North Carolina, which Obama won in 2008. The Romney campaign had tried to put the three blue-leaning Midwestern states in their column in the final weeks of the campaign, holding rallies and making appearances there.

At the earliest, the race will be called at 11 p.m. ET, when the West Coast polling stations close and elections officials will have had time to tabulate ballots in some swing states. But if the race ends up extremely close in a few states, it could take days, or even weeks, to declare a winner.

A shrinking electoral battleground this year means that only 12 states are really seen as in play, and their results are the ones political junkies—and the campaigns—will anxiously be awaiting. Though national polls show the two candidates in a dead heat, Obama leads in most of these battleground states' recent polls. The president could get to 270 electoral votes—which is the number needed to win—by taking only four battleground states: Wisconsin, Nevada, Pennsylvania and Ohio. Romney needs at least five of the 11 states, including Ohio, to get to victory.

The swing states of Virginia and Florida, where polls have already closed, are among the states seen as must wins for Romney if he is to garner 270 votes.

Another state crucial to both Obama and Romney's path to victory is Ohio, where voting ended at 7:30 PM. The Buckeye State tends to vote a bit more Republican than the nation as a whole, but polling there suggests that Obama has been able to reverse that trend and hold an edge there over Romney, perhaps due to the president's support of the auto bailout three years ago. But some have suggested the state polling in Ohio has underestimated Republican voters' enthusiasm and overestimated turnout among groups that tend to vote Democratic.

Both campaigns demonstrated how important Ohio was to their campaigns on Tuesday. Romney and his running mate Paul Ryan spent Tuesday campaigning in the Cleveland area, while Vice President Joe Biden made an unannounced trip to the state to make a last-minute appeal to its voters.