CHICAGO -- President Barack Obama's campaign was relishing a hard-fought victory for the presidency, capping a re-election bid that hinged heavily on aggressive voter registration and turnout efforts.

Obama and his team were scattered across his hometown of Chicago as supporters awaited the president's victory speech. The president celebrated his win with his family at a downtown hotel. Hundreds of staffers watched the returns come in at the campaign's nearby headquarters, then streamed out of the high-rise building to attend the president's speech. And senior staffers at the convention center mused about how much earlier the election outcome was determined.

An ecstatic crowd had been assembling in the cavernous hall for hours, watching the returns on giant screens before erupting in a deafening roar and a swirl of waving flags at the news that he had won.

The president's team had projected confidence for days, but nervously watched the election returns roll in Tuesday night. Even as the race appeared to be turning in Obama's direction, the staff was narrowly focused on Ohio, the Midwest swing state where Obama and Republican Mitt Romney competed fiercely.

Obama shuttled back and forth Tuesday between the downtown hotel and his South Side home, where he ate dinner with his family. The Obamas decamped to the hotel around 10:30pm EST to watch the final results come in.

Despite their outward confidence, Obama and his aides left 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.

The game resulted in Obama's first victory of the day.

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.

One tradition Obama kept, however, was his Election Day basketball game.

A savvy basketball fan, Obama was joined by former Chicago Bulls star Scottie Pippen, childhood friends Mike Ramos and Marty Nesbitt, and Education Secretary Arne Duncan, a former captain of Harvard's basketball team.

Others who played included Obama's chef Sam Kass, first lady Michelle Obama's brother Craig Robinson, former Bulls player Jeff Sanders, and Alexi Giannoulias, the former Illinois state treasurer and 2010 Democratic U.S. Senate nominee.