"You voted for action, not politics as usual," Obama said in his address, but there was little sign that his call would be answered, with the president facing the prospect of doing business with a hostile Republican-led House of Representatives for at least the next two years and a looming showdown over spending and debt – the so-called "fiscal cliff".
Unlike after his election in 2008, the president is unlikely to be given a honeymoon period.
Both the Republican House speaker, John Boehner, and the Democratic leader in the Senate, Harry Reid, spoke about a need to work together to resolve the crisis, but it could turn into one of the biggest clashes yet between the White House and Congress under Obama's presidency.
While Obama easily beat off the challenge from his Republican opponent Mitt Romney, holding swing state after swing state, the election provided yet another reminder of just how divided America remains.
While the inauguration is not until January, in effect Obama embarked on his second term on Wednesday. Having disappointed many supporters in his first term, he is looking now to establish a legacy that will transform him from a middling president into a great one.
As well as overseeing what he hopes will be continued economic recovery, he hopes to address issues ranging from immigration reform to investment in education and climate change, and, in foreign policy, from Iran to Israel-Palestine.
As well as comfortably winning more than the required 270 electoral college votes, he also secured a higher share of the popular vote, giving him a mandate for his struggles with the Republican-led House. House Republicans, however, may not view it as a mandate.
Boehner, in a statement on Wednesday, sounded conciliatory. He cited "the need for both parties to find common ground and take steps together to help our economy grow and create jobs, which is critical to solving our debt". Obama is reported to have phoned Boehner on Wednesday to begin negotiation.
Reid, so often at odds with Boehner, also sounded conciliatory, saying: "I look at the challenges that we have ahead of us and I reach out to my Republican colleagues in the Senate and the House. Let's come together. We know what the issues are, let's solve them."
Obama, in an initially off-the-record interview during the campaign, expressed optimism of a "grand bargain" with the Republicans, one that eluded him last year. The trouble will come when talks move to detail, with the Republicans wanting to protect military spending while the Democrats seek cuts. Obama has called for tax increases on households earning more than $250,000 (£156,000); Boehner has rejected any tax increases.
Shares dropped on the Dow in anticipation of continued gridlock. By lunchtime, all the major US markets were down over 300 points.
The new House, which will be formed in January, will look much like the existing one, which has a huge Republican majority. The Senate too remained little changed, with the Democrats retaining their slim majority, gaining three and losing one.
In the presidential race, Romney won only one of the swing states, North Carolina, while Obama held New Hampshire, Virginia, Ohio, Wisconsin, Nevada, Iowa and Colorado.
As of this afternoon the winner of Florida's 29 electoral college votes remained undecided. With the votes still being counted, the question was whether the result would fall within the margin that automatically requires a recount.
Whatever the result in Florida the election was chaotic, with huge lines forming in Miami-Dade, which were blamed by some on Republican machinations to discourage Democrats from voting. Florida's Republican legislature had been throwing up obstacles with voter ID laws and effectively preventing civic groups from registering voters, both of which were struck down by federal courts. Adding to the delays were the longest ballots in Florida's history after Republicans added lengthy, complicated constitutional amendments.
"Our governor and rightwingers intentionally made it difficult to vote," Florida congresswoman Kathy Castor said.
In his victory speech in Chicago, Obama referred to the long queues to vote and said there was a need for electoral reform.
He returned to the soaring rhetoric that was his trademark during the 2008 election but which he dispensed with in 2012. Amid the disillusionment with his presidency and the tough economic conditions, his campaign team decided it was inappropriate.
But having won, he returned not only to the oratory but to famous lines from earlier speeches, reprising once again his 2008 slogan about "hope".
Stepping up to the lectern to the upbeat strains of Stevie Wonder's Signed, Sealed, Delivered, I'm Yours, Obama told the ecstatic crowd of supporters: "Tonight in this election, you, the American people, reminded us that while our road has been hard, while our journey has been long, we have picked ourselves up, we have fought our way back. And we know in our hearts that for the United States of America the best is yet to come." In a speech that lasted more than 25 minutes, after paying emotional tribute to his wife, Michelle, and his daughters, Malia and Sasha – as well as to his vice-president, Joe Biden – Obama returned to the message that first brought him to national attention.
"We are not as divided as our politics suggests," he said. "We're not as cynical as the pundits believe. We are greater than the sum of our individual ambitions, and we remain more than a collection of red states and blue states. We are, and forever will be, the United States of America."
Obama made clear he had an agenda in mind for his second term, citing changes in the tax code, immigration reform and, as he put it, an America "that isn't threatened by the destructive power of a warming planet".
Shortly beforehand, Romney had phoned the president to concede. In a gracious concession speech in Boston, Romney told his supporters: "The nation, as you know, is at a critical point. At a time like this, we can't risk partisan bickering and political posturing. Our leaders have to reach across the aisle to do the people's work."
He continued: "This is a time for great challenges for America and I pray the president will be successful in guiding our nation."
Romney paid tribute to his wife, Ann, and running-mate, Paul Ryan, as he said they had given everything to the campaign. "Paul and I have left everything on the field. We have given our all to this campaign. I so wish – I so wish that I had been able to fulfill your hopes to lead the country in a different direction. But the nation chose another leader."
The campaign almost throughout has been a referendum on Obama. Although there was widespread disillusionment with the slow pace of economy recovery and a high unemployment level, Americans decided to stick with the incumbent.
Historically, it would have been a disappointment for African Americans and many white liberals if the first black presidency had ended in failure, halted prematurely.
Romney fought a largely lacklustre campaign, with only one flash, his overwhelming win over Obama in the first presidential debate on 3 October.
On Wednesday the Republicans embarked on a post-mortem that threatens to be bloody.
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image: © Aaron Logan