Barack Hussein Obama was re-elected president of the United States on Tuesday, overcoming powerful economic headwinds, a lock-step resistance to his agenda by Republicans in Congress and an unprecedented torrent of advertising as a divided nation voted to give him more time.
In defeating Mitt Romney, the president carried Colorado, Iowa, Ohio, New Hampshire, Virginia and Wisconsin, a near sweep of the battleground states, and was holding a narrow advantage in Florida. The path to victory for Mr. Romney narrowed as the night wore along, with Mr. Obama winning at least 303 electoral votes.
A cheer of jubilation sounded at the Obama campaign headquarters in Chicago when the television networks began projecting him as the winner at 11:20 p.m., even as the ballots were still being counted in many states where voters had waited in line well into the night. The victory was far narrower than his historic election four years ago, but it was no less dramatic.
“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,” Mr. Obama told his supporters early Wednesday. “We know in our hearts that for the United States of America, the best is yet to come.”
Mr. Obama’s re-election extended his place in history, carrying the tenure of the nation’s first black president into a second term. His path followed a pattern that has been an arc to his political career: faltering when he seemed to be at his strongest — the period before his first debate with Mr. Romney — before he redoubled his efforts to lift himself and his supporters to victory.
The evening was not without the drama that has come to mark so many recent elections: For more than 90 minutes after the networks projected Mr. Obama as the winner, Mr. Romney held off calling him to concede. And as the president waited to declare victory in Chicago, Mr. Romney’s aides were prepared to head to the airport, suitcases packed, potentially to contest several close results.
But as it became increasingly clear that no amount of contesting would bring him victory, he called Mr. Obama to concede shortly before 1 a.m.
“I wish all of them well, but particularly the president, the first lady and their daughters,” Mr. Romney told his supporters in Boston. “This is a time of great challenges for America, and I pray that the president will be successful in guiding our nation.”
Hispanics made up an important part of Mr. Obama’s winning coalition, preliminary exit poll data showed. And before the night was through, there were already recriminations from Republican moderates who said Mr. Romney had gone too far during the primaries in his statements against those here illegally, including his promise that his get-tough policies would cause some to “self-deport.”
Mr. Obama, 51, faces governing in a deeply divided country and a partisan-rich capital, where Republicans retained their majority in the House and Democrats kept their control of the Senate. His re-election offers him a second chance that will quickly be tested, given the rapidly escalating fiscal showdown.
For Mr. Obama, the result brings a ratification of his sweeping health care act, which Mr. Romney had vowed to repeal. The law will now continue on course toward nearly full implementation in 2014, promising to change significantly the way medical services are administrated nationwide.
Confident that the economy is finally on a true path toward stability, Mr. Obama and his aides have hinted that he would seek to tackle some of the grand but unrealized promises of his first campaign, including the sort of immigration overhaul that has eluded presidents of both parties for decades.
But he will be venturing back into a Congressional environment similar to that of his first term, with the Senate under the control of Democrats and the House under the control of Republicans, whose leaders have hinted that they will be no less likely to challenge him than they were during the last four years.
The state-by-state pursuit of 270 electoral votes was being closely tracked by both campaigns, with Mr. Romney winning North Carolina and Indiana, which Mr. Obama carried four years ago. But Mr. Obama won Michigan, the state where Mr. Romney was born, and Minnesota, a pair of states that Republican groups had spent millions trying to make competitive.
Americans delivered a final judgment on a long and bitter campaign that drew so many people to the polls that several key states extended voting for hours. In Virginia and Florida, long lines stretched from polling places, with the Obama campaign sending text messages to supporters in those areas, saying: “You can still vote.”
Neither party could predict how the outcome would affect the direction of the Republican Party. Moderates were hopeful it would lead the rank and file to realize that the party’s grass-roots conservatism that Mr. Romney pledged himself to during the primaries doomed him in the general election. Tea Party adherents have indicated that they will argue that he was damaged because of his move to middle ground during the general election.
As he delivered his brief concession speech early Wednesday, Mr. Romney did not directly address the challenges facing Republicans. His advisers said that his second failed quest for the White House would be his last, with his running mate, Representative Paul D. Ryan of Wisconsin, standing as one of the leaders of the party.
“We have given our all to this campaign,” said Mr. Romney, stoic and gracious in his remarks. “I so wish that I had been able to fulfill your hopes to lead this country in a different direction.”
The results were more a matter of voters giving Mr. Obama more time than a second chance. Through most of the year slight majorities of voters had told pollsters that they believed his policies would improve the economy if they could stay in place into the future.
Mr. Obama’s campaign team built its coalition the hard way, through intensive efforts to find and motivate supporters who had lost the ardor of four years ago and, Mr. Obama’s strategists feared, might not find their way to polls if left to their own devices.
Up against real enthusiasm for Mr. Romney — or, just as important, against Mr. Obama — among Republicans and many independents, their strategy of spending vast sums of money on their get-out-the-vote operation seemed vindicated on Tuesday.
As opinion surveys that followed the first debate between Mr. Romney and Mr. Obama showed a tightening race, Mr. Obama’s team had insisted that its coalition was coming together as it hoped it would. In the end, it was not a bluff.
Even with Mr. Obama pulling off a new sweep of the highly contested battlegrounds from Nevada to New Hampshire, the result in each of the states was very narrow. The Romney campaign was taking its time early Wednesday to review the outcome and searching for any irregularities.
The top issue on the minds of voters was the economy, according to interviews, with three-quarters saying that economic conditions were not good or poor. But only 3 in 10 said things were getting worse, and 4 in 10 said the economy was improving.
Mr. Romney, who campaigned aggressively on his ability to turn around the deepest economic downturn since the Great Depression, was given a narrow edge when voters were asked which candidate was better equipped to handle the economy, the interviews found.
The electorate was split along partisan lines over a question that drove much of the campaign debate: whether it was Mr. Obama or his predecessor, George W. Bush, who bore the most responsibility for the nation’s continued economic challenges. About 4 in 10 independent voters said that Mr. Bush should be held responsible.
The president built a muscular campaign organization and used a strong financial advantage to hold off an array of forces that opposed his candidacy. The margin of his victory was smaller than in 2008 — he held an advantage of about 700,000 in the popular vote early Wednesday — but a strategic firewall in several battleground states protected his Electoral College majority.
As Mr. Romney gained steam and stature in the final weeks of the campaign, the Obama campaign put its hopes in perhaps one thing above all others: that the rebound in the auto industry after the president’s bailout package of 2009 would give him the winning edge in Ohio, a linchpin of his road to re-election.
Early interviews with voters showed that just over half of Ohio voters approved of the bailout, a result that was balanced by a less encouraging sign for the president: Some 4 in 10 said they or someone in their household had lost a job over the last four years.
He defeated Mr. Romney 52 percent to 47 percent in Hamilton County, home to Cincinnati, but only because of the number of votes he banked in the month leading up to Election Day.
Mr. Obama won despite losing some of his 2008 margins among his key constituencies, including among younger voters, blacks and Jewish voters, yet he appeared to increase his share among Hispanics and Asians. Early exit poll results showed Latinos representing about 1 in 10 voters nationwide, and voting for Mr. Obama in greater numbers than four years ago, making a difference in several states, including Colorado and Florida.
He held on to female voters, according to preliminary exit polls conducted by Edison Research, but he struggled even more among white men than he did four years ago.
Mr. Romney’s coalition included disproportionate support from whites, men, older people, high-income voters, evangelicals, those from suburban and rural counties, and those who call themselves adherents of the Tea Party — a group that had resisted him through the primaries but had fully embraced him by Election Day.
The Republican Party seemed destined for a new round of self-reflection over how it approaches Hispanics going forward, a fast-growing portion of the voting population that senior party strategists had sought to woo before a strain of intense activism against illegal immigration took hold within the Republican grass roots.
It was the first presidential election since the 2010 Supreme Court decision loosening restrictions on political spending, and the first in which both major-party candidates opted out of the campaign matching system that imposes spending limits in return for federal financing. And the overall cost of the campaign rose accordingly, with all candidates for federal office, their parties and their supportive “super PACs” spending more than $6 billion combined.
The results Tuesday were certain to be parsed for days to determine just what effect the spending had, and who would be more irate at the answer — the donors who spent millions of dollars of their own money for a certain outcome, or those who found a barrage of negative advertising to be major factors in their defeats.
While the campaign often seemed small and petty, with Mr. Romney and Mr. Obama intensely quarreling and bickering, the contest was actually rooted in big and consequential decisions, with the role of the federal government squarely at the center of the debate.
Though Mr. Obama’s health care law galvanized his most ardent opposition, and continually drew low ratings in polls as a whole, interviews with voters found that nearly half wanted to see it kept intact or expanded, a quarter wanted to see it repealed entirely and another quarter said they wanted portions of it repealed.
In Chicago, as crowds waited for Mr. Obama to deliver his speech, his supporters erupted into a roar of relief and elation. Car horns honked from the street as people chanted the president’s name.
“I feel like it’s a repudiation of everything the Republicans said in the campaign,” said Jasmyne Walker, 31, who jumped up and down on the edge of a stone planter in a downtown plaza. “Everybody said that if he lost it would be buyer’s remorse — that we were high on hope in 2008. This says we’re on the right track. I feel like this confirms that.”
By JEFF ZELENY and JIM RUTENBERG