WASHINGTON -- President Barack Obama won re-election Tuesday night despite a fierce challenge from Mitt Romney as well as a weak economy and high unemployment that crimped the middle class dreams of millions.
"This happened because of you. Thank you" he tweeted to supporters" as he secured four more years in the White House.
Obama aides said their internal numbers had them on track for victory. And staffers at the president's campaign headquarters in Chicago were cheering and high-fiving as the results came in.
Still, the campaign was laser-focused on the 18 electoral votes in Ohio, the Midwest swing state where Obama and Republican Mitt Romney competed fiercely. The Associated Press called the election for Obama shortly after it became clear that Obama won Ohio.
The Democratic ticket was optimistic about its prospects in the state where the president's bailout of the auto industry is widely popular.
Obama's team was also closely watching Florida to see if more Democratic votes materialized in a state that Obama won in 2008. Yet the president doesn't need a victory there to reach the required 270 Electoral College votes.
Obama, along with his wife and daughters, left his Chicago home around 10:30 p.m. EST and headed to the downtown hotel where several longtime aides were watching the election results. The Obamas were expected to stay at the hotel until the race is called.
Despite their outward confidence, Obama and his aides were leaving nothing to chance. The president indulged his superstitions by engaging in a traditional Election Day basketball game with friends, as the race that will determine his political future was finally in the hands of voters.
Obama's team won, ensuring him at least one victory Tuesday.
The president kicked off Election Day with a surprise visit to a campaign office near his South Side home.
Thunderous applause from about two dozen volunteers, many with tears streaming down their faces, greeted Obama. Removing his suit coat, he sat down to make some calls to volunteers in neighboring Wisconsin. "Let's get busy," he said.
"Hopefully we'll have a good day," he said on one call. "Keep working hard all the way through."
Speaking to reporters afterward, Obama said: "We feel confident we've got the votes to win but it's going to depend ultimately on whether these votes turn out."
The president also congratulated his Republican rival Mitt Romney on running "spirited campaign", saying he knew the GOP nominee's supporters were "just as engaged, just as enthusiastic" as his own.
Late Tuesday, Michelle Obama issued a message through Twitter thanking supporters: "I am so grateful to every one of you for your support and your prayers. -mo"
The president headed into Election Day locked in a close race with Romney, according to national polls. But he appeared to have a slight edge in some key battlegrounds that will decide the contest, including Ohio, Iowa and Wisconsin.
Obama said late Tuesday in an interview with Denver television station KDVR that he had prepared both a victory speech and a concession speech for election night.
"You always have two speeches prepared because you can't take anything for granted," Obama said. Romney on Tuesday told reporters he has only prepared a victory speech.
There was no traditional Election Day photo of Obama voting Tuesday because he did so in Chicago last week, part of his campaign's effort to promote early voting. First lady Michelle Obama voted by absentee ballot.