Obama and his family spent the night at his home in Chicago's Kenwood neighborhood at the end of a day on which he won re-election with 25 states and the District of Columbia. He was leading 50 percent to 49 percent in Florida with 97 percent of the precincts reporting.
Vice President Joe Biden flew back to Delaware before the first family's motorcade left for O'Hare International Airport to board Air Force One.
Bystanders cheered and applauded as Obama's motorcade passed on Michigan Avenue, and the president made a stop at his campaign headquarters in the Prudential Building to thank staffers and volunteers for their hard work. Campaign workers gave him a standing ovation, and some stood on desktops to listen to the president, who lingered more than an hour shaking hands.
As it did in 2008, Valois restaurant in Hyde Park, an Obama favorite, gave out free breakfasts of eggs, potatoes and sausage or bacon until it ran out of food. Supporters from all over the country had traveled to Chicago to attend Tuesday night's victory party at the lakefront McCormick Place Exposition Center.
"We were all hugging each other, black and white," said TyRon Turner, a small-business owner from Inglewood, Calif. "I said to someone, 'Look at all the different races in this room.' We were all Americans, as we should be. This is what America looks like."
Obama returns to the White House facing the same deeply divided Congress, with Democrats in control of the Senate and Republicans in control of the House.
"I return to the White House more determined and more inspired than ever about the work there is to do and the future that lies ahead," Obama told supporters at an early morning Chicago victory celebration.
"The president reiterated his commitment to finding bipartisan solutions to reduce our deficit in a balanced way, cut taxes for middle-class families and small businesses, and create jobs," the White House said.
Biden talked to reporters as he headed east aboard Air Force Two. Asked what he took away from Tuesday's outcome, he said: "We've got a lot of work to do. I talked to the president. We're really anxious to get moving on, first of all, dealing with the first things first, this fiscal cliff. I think we can do it. I think the real takeaway is what is the takeaway going to be on the part of our Republican colleagues.
"What judgment are they going to make? And having been a Democrat elected in 1972 by 3,200 votes, I know it takes a little time to kind of digest what's going on. But I've been talking to a lot of people, made a lot of phone calls. I'm not going to get into who. But I think people know we've got to get down to work and I think they're ready to move."
Biden said he's optimistic Republicans and Democrats will find a way to compromise on such issues as immigration reform, tax policy and the looming sequester -- steep cuts in defense and domestic spending scheduled to go into effect Jan. 1 unless Congress works out a deficit-reduction formula.
"Tonight you voted for action, not politics as usual," a hoarse Obama said in his victory speech.
Republicans held a 240-190 edge in the House going into the election. They were projected to finish the election with at least 239 seats and Democrats with 196, but several races were still undecided Wednesday.
In Florida, incumbent Republican Rep. Allen West was trailing Democrat Patrick Murphy by fewer than 3,000 votes with 100 percent of the votes counted and a possible recount in the offing. In California, veteran Democratic Rep. Henry Waxman fought off independent challenger Bill Bloomfield for a 53 percent to 46 percent victory, the Los Angeles Times reported.
In Arizona, Democrat Ron Barber, a former aide to former Rep. Gabrielle Giffords, trailed Republican Martha McSally by 1,312 votes with 100 percent of the vote counted.
With 100 percent of precincts reporting in Michigan, Republican Rep. Dan Benishek defeated Democrat Gary McDowell by fewer than 3,000 votes, and eight-term Rep. Mike McIntyre, D-N.C., had a 378-vote lead over Republican David Rouzer with 100 percent of the precincts reporting, CNN said.
Republicans, stung by the defeat of Mitt Romney and Paul Ryan, who lost in their home states of Massachusetts and Wisconsin, refused to signal a willingness to compromise. Ryan won re-election in his U.S. House district, as did former GOP presidential candidate Michele Bachmann in neighboring Minnesota.
In Illinois, disabled Iraq War veteran Democrat Tammy Duckworth defeated Republican Tea Party stalwart Rep. Joe Walsh.
"With this vote, the American people have also made clear there's no mandate for raising taxes," Boehner said. "What Americans want are solutions that will ease the burdens on small businesses, bring jobs home and let our economy grow.
"If there is a mandate, it is a mandate for both parties to find common ground and take steps together to help our economy grow and create jobs."
In a gracious concession speech, Romney called for bipartisanship after saying he and Ryan had given their all to try to defeat Obama.
McConnell called for Obama to reach out to Republicans.
"The American people did two things: They gave President Obama a second chance to fix the problems that even he admits he failed to solve during his first four years on office, and they preserved Republican control of the House of Representatives," he said in a statement.
"Now it's time for the president to propose solutions that actually have a chance of passing the Republican-controlled House of Representatives and a closely divided Senate, step up to the plate on the challenges for the moment, and deliver in a way that he did not in his first four years in office."
Democrats picked up three key seats in the Senate, with Elizabeth Warren ousting one-term Republican Scott Brown in Massachusetts, Rep. Joe Donnelly defeating Republican Richard Mourdock in Indiana and Rep. Tammy Baldwin beating former Republican Wisconsin Gov. Tommy Thompson. Baldwin becomes the first openly gay member in the Senate.
In another closely watched Senate race, Democrat Claire McCaskill won re-election in Missouri and Democratic former Virginia Gov. Tim Kaine defeated Republican former Gov. George Allen for the seat of retiring Democratic Sen. Jim Webb.
Democrats also picked up a seat in Maine, where independent candidate Angus King, who is expected to caucus with the Democrats, won the seat vacated by retiring Republican Sen. Olympia Snowe.
In Connecticut, Democratic Rep. Chris Murphy defeated Republican Linda McMahon, and in West Virginia Democrat Joe Manchin won his first full term by defeating Republican businessman John Raese. Manchin won a special election in 2010 to complete the term of the late Sen. Robert Byrd.
Democrats won gubernatorial races in Missouri, West Virginia, Vermont, New Hampshire, Delaware and Montana, while Republicans won in Indiana, Utah, North Dakota and North Carolina. Washington state's governor race was undecided, with Democrat Jay Inslee leading Republican Rob McKenna 51 percent to 49 percent with 55 percent of precincts reporting.