President Barack Obama won a second term on Tuesday, emerging from a long, punishing campaign with a new mandate to lead a divided and anxious nation.

"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," Obama said in a victory speech in his hometown of Chicago. "We have fought our way back and we know in our hearts for the United States of America, the best is yet to come."

For full Decision 2012 coverage, visit NBCNews.com.

Obama said his re-election came with a sense of accomplishment and a new surge of hope.

"Our economy is recovering. A decade of war is ending. A long campaign is now over," he said. "And whether I earned your vote or not, I have listened to you. I have learned from you. And you've made me a better president. And with your stories and your struggles, I return to the White House more determined and more inspired than ever about the work there is to do and about the future and life ahead."

But the cold reality is that when he arrives back in Washington, the president will face the same obstacles he did before the election. With Republicans maintaining control of the House of Representatives, the era of political gridlock will likely continue.

That challenge was articulated by one of his most outspoken opponents, Sen. Mitch McConnell, leader of Senate Republicans.

"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 of the moment, and deliver in a way that he did not in his first four years in office," McConnell said. “To the extent he wants to move to the political center, which is where the work gets done in a divided government, we’ll be there to meet him half way."

Obama's triumph unfolded incrementally Tuesday night, as he racked up a string of victories in crucial battlegrounds. One after another, states that had been deemed competitive swing states before Election Day fell into the president's hands.

Pennsylvania. Wisconsin. New Hampshire. Iowa. Virginia. With each Obama win, the path to victory for his opponent, former Massachusetts Gov. Mitt Romney, got narrower.

Finally, just after 11 p.m. ET, NBC News projected Obama to win Ohio, his so-called "firewall" and the one state that has sided with the winning presidential candidate in every election since 1960. Obama's win there, thanks in large part to the state's support of his bailout of the auto industry, handed him the Electoral College swing votes he needed.

Romney conceded the race in a phone call to the president just before 1 a.m. ET. He then took the stage at the Westin Boston Waterfront Hotel, telling supporters that he wished the president well.

"This is a time of great challenges for America, and I pray that the president will be successful in guiding our nation," Romney said.

Obama's battleground victories were so authoritative that Florida, which was considered the biggest prize, wasn't even a factor.

Florida was the only state that remained too close to call as of 6:00 a.m. ET. Its results won't be known until after the start of business Wednesday.

So many people turned out to vote Tuesday that Ohio, Florida and Virginia kept polls open long after official closing times to accommodate the people waiting in long lines that snaked from the doors of polling places.

Exit polls indicated that Obama was favored among women, young adults, singles and Latinos — the last group by wider margins than in 2008.

"Today is the clearest proof yet that, against the odds, ordinary Americans can overcome powerful interests," Obama wrote in an email to supporters.

The first person Obama called after getting the concession call from Romney was former President Bill Clinton, a campaign official told NBC News.

The former president was one of Obama’s top surrogates, and onlookers credited his speech at the Democratic National Convention in Charlotte with Obama's "Clinton bump" in the polls.

Obama, Romney and their proxies spent nearly $2 billion, a record amount for a presidential campaign.

In his concession speech, Romney said he had no regrets and hoped that the country would move past its partisan differences to solve the nation's problems.

"I so wish that I had been able to fulfill your hopes to lead the country in a different direction," he said. "But the nation chose another leader."

Less than an hour later, at about 1:45 a.m. ET, Obama appeared before a roaring crowd at the McCormick Place convention center in Chicago. His wife, Michelle, and their two daughters accompanied him on stage while Stevie Wonder's "Signed, Sealed, Delivered" blasted. Then they left him to deliver his victory speech.

Obama congratulated Romney "on a hard-fought campaign."

“We may have battled fiercely, but it's only because we love this country, we care so strongly about its future," he said.

The president went on to say that the rancor and rift that characterized the campaign was understandable, given the nation's challenges.

"That won't change after tonight. And it shouldn't. These arguments we have are a mark of our liberty, and we can never forget that as we speak, people in distant nations are risking their lives right now just for a chance to argue about the issues that matter, the chance to cast their ballots like we did today."

Obama, 51, the country’s first black president, won election in 2008 on a promise of hope and change, but he triumphed this time with a starkly different message: asking voters to stick with him as he continues trying to fix the economy and improve America’s standing in the world.

He defeated Romney, 65, a wealthy venture capitalist who’d been running for president for the better part of a decade. A win for Romney would have been vindication, of sorts, for his family; his father, George, ran unsuccessfully for the Republican presidential nomination in 1968.

The 2012 race highlighted two contrasting visions of the country. Where Romney emphasized the need to lower taxes, relax federal regulations and cut government spending, Obama promised to raise taxes on the wealthiest Americans and deploy government’s help in pulling the country out of the economic doldrums.

Despite his image as stiff and disinterested in the plight of the middle class, Romney managed to make the race close by appealing to many voters’ disappointment in Obama and widespread anxiety about the economy. Romney promised to bring a businessman’s sensibility to the job, a point he drove home in the first presidential debate, which he dominated. That performance sparked a surge in the polls that made the race tight right up until Election Day.

But Romney, in the end, was not able to fully convince an edgy public that he could do a better job than Obama. Nor was Romney able to overcome Obama’s image as a more likable guy.

Now Romney may well have run his last race for public office.

Obama will begin his second term no longer a symbol of political catharsis but as a flawed but adaptive leader who took a lot of lumps and learned from them.

The president's re-election means there will likely be no overturning of his signature domestic policy achievement, the 2010 health care reform law. Obama has also promised to raise taxes on those earning more than $250,000 a year.

Obama must also make good on his campaign promises to finally correct America’s economic path by finding ways to add a million more manufacturing jobs, boost domestic energy production, reduce the county’s carbon footprint, shore up Medicare, cut students' college loan costs and slash the national deficit by $4 trillion.

When he returns to the White House, he won’t have much time to savor his victory, because he’ll face the threat of a year-end "fiscal cliff," when a series of tax cuts are set to expire and massive government spending cuts go into effect.

As he noted in his email to supporters Tuesday night: "There's a lot more work to do."