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NBC News has projected that President Barack Obama will win a second term after he racked up a string of victories in crucial battleground states.
In an email to supporters before taking the stage for his victory speech in Chicago, Obama credited them for his victory.
"I want you to know that this wasn't fate, and it wasn't an accident. You made this happen," the president wrote.
For full Decision 2012 coverage, visit NBCNews.com.
One after another Tuesday night, crucial states that had been deemed toss-ups before Election Day fell into the president's hands: Pennsylvania, Wisconsin, New Hampshire, Iowa. With each Obama win, the path to victory for Romney got narrower and more demanding.
Finally, the results in Ohio put Obama over the top, handing him the Electoral College votes he needed to remain at the reins of a divided and anxious nation. Ohio has sided with the winning candidate in every presidential election since 1960.
"Today is the clearest proof yet that, against the odds, ordinary Americans can overcome powerful interests," Obama wrote in his email to supporters. He added: "There's a lot more work to do."
Romney's campaign director in Ohio, Scott Jennings, told NBC News the Romney campaign was not conceding Ohio.
So many people turned out to vote Tuesday that several crucial states, including Ohio, Florida and Virginia, remained open after closing to accommodate the people who waited in long lines that snaked from the doors of polling places.
Obama, the country's first black president who won election in 2008 on a promise of hope and change, 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 survived a long, punishing, exorbitant race against former Massachusetts Gov. Mitt Romney that 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.
Obama's win also means that his signature piece of legislation, the over haul of the country's health-care system, will remain law.
The president's re-election, along with what appears to be no change in the balance of power Congress, means that, in broad terms, nothing that much will change in Washington.
The nail-biter that polls had been predicting for weeks didn't turn out to be much of one.
With so much riding on relatively few votes, the campaigns remained in war mode even after the candidates themselves stopped campaigning. Lawyers on both sides spent the day wrangling over early voting procedures, voter-identification requirements and the counting of provisional and absentee ballots.
Thousands of people struggled to vote in areas battered by Hurricane Sandy. Long lines and mass frustration dominated parts of the two states where many people had no place to live, let alone vote. In New York and New Jersey, officials scrambled for backup generators, and many residents were forced to travel to polling places outside of their neighborhoods. New Jersey Gov. Chris Christie made a last-minute decision to allow victims who lost their homes to vote by email.
More than 30 million people, Obama among them, have taken advantage of early-voting laws and cast their ballots ahead of time.
The election offered a choice between two starkly different men: the buttoned-up, business-savvy Romney, and the still-popular but battle-scarred Obama.
But it was much more than that. It was also a decision about the role of government in American life; who ought to pay more taxes; the future of entitlement programs like Medicare and Medicaid; and the survival of Obama's signature domestic legislation, the overhaul of the country's health-care system.
At its core, the election reflected who the majority of America believed is better equipped to lead the country out of the economic doldrums, which has pushed record number of people to food stamps and other public assistance, and unemployment to 7.9 percent.
Obama will also have the power to remake the Supreme Court. Several justices have reached retirement age, meaning that whoever takes office in January could get the opportunity to tip the court's political makeup in his favor.
Obama, 51, was elected in 2008 on a promise of hope and change but was tested from the get-go. He inherited a near-collapse of the economy and national malaise over two lengthy wars. He was unable to rise above the partisan rancor of Washington, and his checkered first term left him bruised and humbled, but also adaptive. He claims that the economy would have been much worse if it wasn't for the economic stimulus bills he pushed through Congress, and counts among his top achievements a bailout of the American auto industry, the adoption of his health-care reform initiative, the education-reform program called Race to the Top.
Romney, 65, a wealthy venture capitalist who saved the 2002 Winter Olympics in Salt Lake City from insolvency, first ran for president four years ago and never really stopped. His campaign focused on Obama's shaky economic record, promising to bring a businessman's experience to the problem.
Just a couple months ago, Romney was seen as headed for a landslide defeat, but he rallied with a dominant performance in the first of three presidential debates. That showing nearly eliminated Obama's lead, and the race remained tight until Election Day.
