Barack Obama re-elected

President Barack Obama won re-election to a second term in the White House on Tuesday, television networks projected, beating Republican challenger Mitt Romney after a long and bitter campaign.

Obama defeated Romney in a series of key swing states despite a weak economic recovery and persistent high unemployment as US voters decided between two starkly different visions for the country.

Obama's narrow wins in Ohio, Wisconsin, Iowa, Pennsylvania and New Hampshire - all states that Romney had contested - effectively ended Romney's hopes of capturing the 270 electoral votes needed to clinch the White House.

At least 120 million American voters were expected to cast votes in the race between the Democratic incumbent and Romney after a campaign focused on how to repair the ailing US economy.

Obama enters his second four-year term faced with a difficult task of tackling $1 trillion annual deficits, reducing a $16 trillion national debt, overhauling expensive social programs and dealing with a gridlocked US Congress that looked likely to maintain the same partisan makeup.

The Republican's chances were hit by Obama victories in Wisconsin and Pennsylvania, as well as New Hampshire. Romney last week visited Wisconsin, home state of his vice presidential running mate, Paul Ryan, and had stopped in Pennsylvania earlier on Tuesday in hopes of pulling off a surprise win there.

In a victory that also limited Romney's path to a victory, Obama won Michigan, the Republican's state of birth but where he ran afoul of voters by opposing an auto industry bailout pushed by Obama. Some polls had shown a tight race there.

Television networks projected Romney the winner, as expected, in Republican states Alabama, Tennessee, Mississippi, Kentucky, West Virginia, Oklahoma, South Carolina and Indiana. He was declared the winner in Texas, Kansas, Louisiana, Nebraska, North Dakota and South Dakota.

Obama was projected the winner in the Democratic strongholds of New York, New Jersey, Maryland, Vermont, Connecticut, Delaware, Massachusetts and his home state of Illinois, as well as Washington, D.C.

Last minute push

Romney voted at a community center near his home in a Boston suburb, before dashing off for a pair of last-minute stops, including in Ohio. "I feel great about Ohio," he said when asked about a state that is considered a must-win for him.

Obama, settling into his hometown of Chicago, made a final pitch to morning commuters in battleground states that have been an almost obsessive focus of both campaigns seeking to map out their paths to victory. He also made a surprise visit to a Chicago campaign office.

As Americans headed to voting booths, campaign teams for both candidates worked the phones feverishly to mobilize supporters to cast their ballots.

Polls closed in Indiana and Kentucky atoday, with voting ending across the country over the following six hours. Ohio closes at 7:30 p.m. EST.

The first results, by tradition, were tallied in Dixville Notch and Hart's Location, both in New Hampshire, shortly after midnight (0500 GMT). Obama and Romney each received five votes in Dixville Notch. In Hart's Location, Obama had 23 votes to nine for Romney and two for Libertarian candidate Gary Johnson.

A familiar scenario

The close race raises the prospect of a disputed outcome similar to the 2000 election, which ended with a US Supreme Court decision favoring George W. Bush over Al Gore after legal challenges to the close vote in Florida. Both the Romney and Obama campaigns have assembled legal teams to deal with possible voting problems, challenges or recounts.

Complaints about voting procedures and possible irregularities surfaced sporadically across the electoral map, with frustrations running high in storm-battered New York and New Jersey. But there was no immediate claim of anything widespread or systematic enough to cast doubt on the credibility of the election outcome.

The balance of power in the US Congress also will be at stake in races for the Senate and House of Representatives that could affect the outcome of "fiscal-cliff" negotiations on spending cuts and tax increases, which kick in at the end of the year unless a deal is reached.

Obama's Democrats are now expected to narrowly hold their Senate majority, while Romney's Republicans are favored to retain House control.

A very tight race

Despite uncertainty about the outcome of the presidential election, US stocks climbed on speculation that it would produce a clear winner. World stock exchanges also rose, but the election kept trading subdued. "It's a relief that hopefully the election will be over," said Fred Dickson, chief market strategist at D.A. Davidson & Co. in Lake Oswego, Oregon.

Despite the weak economy, Obama appeared in September to be cruising to a relatively easy win after a strong party convention and a series of stumbles by Romney, including a secretly recorded video showing the Republican writing off 47 percent of the electorate as government-dependent victims.

But Romney rebounded in the first presidential debate on October 3 in Denver, where his sure-footed criticism of the president and Obama's listless response started a slow rise for Romney in polls. Obama delivered much stronger performances in two subsequent debates and has been praised in recent days for taking the lead in federal relief efforts for victims of superstorm Sandy in the New York-New Jersey area.

The presidential contest is now likely to be determined by voter turnout, and weather could be a factor. Much of the nation was dry and mild, though rain was forecast later on Tuesday in the Southeast, including Florida, an important swing state.

In the closing act of the 2012 election drama, both men expressed confidence in winning. But Obama hedged slightly,

Voting appeared to go smoothly in most places. But thousands of voters in New York and New Jersey encountered confusion and frustratingly long lines. Polling stations there were among thousands of buildings damaged by superstorm Sandy eight days ago.

Obama and Romney raced through seven battleground states on Monday, courting the last remaining undecided voters.

The president wrapped up his tour in Des Moines, Iowa, on Monday with a speech that hearkened back to how the state helped launch his candidacy of "hope and change" in 2008. He wiped away tears as he reflected on his political journey.

Romney ended Monday in Manchester, New Hampshire, where he started his campaign last year. "We're one day away from a fresh start," he told a rally.

Obama ridiculed Romney's claims to be the candidate of change and said the challenger would be a rubber stamp for a conservative Tea Party agenda. Romney argued that four more years of Obama could mean another economic recession.

The common denominator for both was Ohio. Without its 18 electoral votes, the path to victory is very narrow for Romney. No Republican has won the White House without winning the state.

Polls have shown Obama with a small but steady lead in Ohio, due in part by his support for a federal bailout of the auto industry, which accounts for one of every eight jobs there. That undercut Romney's central argument that his business experience made him uniquely qualified to create jobs