President Obama has been declared the winner in Michigan and Pennsylvania, a state Romney had hoped to pick off in the final days of the campaign.
While Romney holds a 152-143 vote lead over Obama in the Electoral College, according to initial projections by CNN and The Associated Press, losing Pennsylvania makes his path to 270 electoral votes more difficult.
Most networks projected Obama as the winner of Michigan quickly after polls closed in the state at 9 p.m., and Fox, ABC and NBC both projected Obama as the winner in Pennsylvania.
The networks have held off on projections in the swing states of Virginia, North Carolina, Ohio, Florida, New Hampshire, Colorado and Wisconsin. Exit polls in several swing states suggest the two campaigns could be in for a long night.
Romney was projected as the winner in Kentucky, Indiana, South Carolina, Georgia, Alabama, Oklahoma, West Virginia, Tennessee, Arkansas, Kansas, Louisiana, Nebraska, North Dakota, South Dakota, Texas, Wyoming and Mississippi. He is also projected to win three of Nebraska's five electoral votes.
Obama was projected as the winner in Vermont, Connecticut, Delaware, Illinois, Maryland, Massachusetts, Rhode Island, the District of Columbia, New York, New Jersey and Michigan. He is projected to win three of Maine's four electoral votes.
Polls have also closed in Missouri, Arizona and New Mexico, but no projections have yet been made.
Romney is awaiting election returns in Boston, while Obama awaits returns in Chicago.
In Virginia, it appeared Mitt Romney was outperforming John McCainJohn McCainSenate committee to vote Monday on Tillerson Trump fails to mention Clinton in inaugural address Hillary Clinton under microscope at inauguration MORE in Northern Virginia exurbs including Loudoun and Prince William counties — areas where the Obama campaign had hoped to bank votes to offset Republican advantages in the southwestern part of the state.
Multiple Republicans pointed to exit poll data that showed voters under the age of 30 representing just 16 percent of the Virginia electorate, down 5 points from 2008. Younger voters backed Obama by a 3-2 margin in 2008, and dampened enthusiasm could provide Romney an edge in then state.
Polls closed in Virginia at 7 p.m., but the state's laws allow voters in line by that time to vote. The Obama campaign in a text message asked volunteers to go to polling sites to ensure those in line get to vote.
In Orlando, Fla., early results showed the president matching his 2008 totals, when he carried the state by 3 points. And a exit poll of the state gave the president a 51 to 48 percent advantage there.
The Republican's win in Indiana is his first takeaway from Obama. The president won a surprise victory in the Hoosier State in 2008, which he was not expected to repeat this year.
According to Romney aides, the candidate was watching the returns come in with family, including his grandchildren, in a hotel suite adjacent to the convention center where he planned to address supporters later in the night.
The mood at the convention center in Chicago, where Obama was expected to take the stage later in the evening, was tense but optimistic. Aides, who were closely monitoring the results while pacing the convention center's concrete floors, repeatedly said they were "cautiously optimistic" — the "phrase of the night," as one aide put it.
As results poured in from the first states, giving Romney an early lead, one aide said, "We're feeling good.
"This is where we wanted to be," the aide said. "We're just watching this play out."
In Boston, there was little visible reaction from the crowd of supporters gathered at Romney headquarters as an early flood of exit polls and results came in showing close races in states like Florida, Virginia and North Carolina that qualify as must-wins for the Romney campaign.
The crowd murmured nervously as pundits on Fox News suggested that Romney could face an uphill battle against the electoral map in the wake of Superstorm Sandy, and Republican strategists with ties to the campaign said Team Romney had gone "radio silent."
Republicans said they were closely watching a number of bellwether areas: the Northern Virginia exurbs, the suburbs around Richmond, the western suburbs of Denver and the I-4 corridor in Florida. Republicans say those areas could indicate whether Romney will have the ability to surpass expectations in battleground states like Ohio, Wisconsin and Pennsylvania, at least one of which he will likely need to pick off.
Early exit polls show Election Day voters are slightly more Republican than they were in 2008, and are broadly concerned about the state of the U.S. economy.
Six in 10 voters said the economy is their top issue, according to the poll, released by the AP and conducted on behalf of a consortium of media companies.
Less than a quarter of voters said their families were better off than they were four years ago — a point seized on by many Republicans as the results leaked out.
Both the Obama and Romney campaigns projected confidence about the election’s outcome earlier on Tuesday, even as Romney made late stops to Ohio and Pennsylvania and Vice President Biden made a surprise trip to Cleveland.
Romney’s camp touted enthusiasm and strong Election Day voting in Ohio and other states in explaining their confidence.
The GOP nominee was greeted at Pittsburgh’s airport by hundreds of supporters. “That's when you know you're going to win,” Romney remarked to reporters when asked about the support.
Obama’s campaign touted an early-voting advantage, a lead in state polls and its ground game in predicting a good night.
Volunteers for Obama are operating out of more than 5,000 locations in battleground states. A campaign aide said that supporters have signed up for more than 208,000 Election Day shifts.
Republicans, meanwhile, said they were excited by early-voting patterns in the crucial state of Ohio, claiming there are turnout decreases in Obama strongholds and more votes lodged at precincts won by Arizona Sen. John McCain in the 2008 presidential race. In Athens County, home of Ohio University and a district where the president took two out of every three votes, turnout was down 10 percent from 2008.
The GOP said that voting was significantly outpacing the last election in the eastern Cleveland suburbs, considered GOP territory. Romney visited the area Tuesday afternoon, stopping at a campaign headquarters and a Wendy's for lunch.
The Romney campaign said a high turnout would bring decisive victories in the key swing states.
“With a strong ground game in the states and momentum on our side, we are confident we will win this election,” said campaign spokeswoman Amanda Henneberg.
Obama senior campaign adviser David Axelrod touted the early-voting advantage and polls that show the president narrowly ahead or tied in Ohio, Florida, Virginia, Iowa, Wisconsin, Colorado and New Hampshire.
“The greater encouragement comes from the cold, hard data, which is that early vote in every battleground state that has early vote has been very robust in our favor,” Axelrod said on CBS. “And the polling has been very much in our favor.”
Romney senior adviser Kevin Madden, however, said Obama’s early-voting numbers have not been as robust as expected this year. He said high GOP turnout would cancel out whatever advantage the president might have.
“Our high-propensity voters tend to come out on Election Day ... but nothing breeds organization like enthusiasm,” Madden said on CBS. “And the enthusiasm that we have seen all across this country in all these key battlegrounds states is really what is going to make the difference tonight.”
Fittingly, the first election result of the day — in Dixville Notch, a small New Hampshire village that always votes at midnight — came back a 5-5 tie.
—This story was updated at 9:24 p.m.