US Elections | Race to the White House in final sprint

US President Barack Obama and his Republican challenger Mitt Romney are wrapping up their campaigns, hours ahead of an election which polls suggest will tip in Obama's favour.

Just after midnight on Tuesday, polls opened in the tiny northeastern villages of Dixville Notch and Hart's Location, in the swing-state of New Hampshire. The vote was tied 5-5 in Dixville Notch, while in Hart's Location Obama won with 23 votes to Romney's nine. Libertarian Gary Johnson also received a vote. The two villages have enjoyed their first-vote status since 1948, but are not seen to be a national bellwether for the direction the election will go.

Obama made his final campaign appearance in Iowa, and will be spending election day in his home city of Chicago.

Governor Romney, however, is breaking with tradition and continuing his election campaign into polling day itself. He is due to appear in Cleveland, Ohio and Pittsburgh in neighbouring Pennsylvania.

Both candidates have spent the past few weeks storming through a handful of key swing states .

Romney went to Florida, where polls suggest he has the edge, and then to Virginia, New Hampshire and Ohio.

Obama appeared in Iowa, Wisconsin and Ohio, joined at rallies by Bruce Springsteen and rapper Jay-Z.

The election will be decided in just a handful of states, with Ohio in particular seen as crucial to victory.

President Obama closed his re-election campaign in Des Moines, Iowa - the city where his bid for the presidency began in early 2007.

At a late-night rally, he told the crowd that Iowa had started "a movement that spread across the country".

Romney, meanwhile, was due to end his campaign with a late-night rally in New Hampshire but made the surprise announcement that he would extend campaigning into election day itself - visiting Ohio and Pennsylvania on Tuesday.

Obama and Romney are running almost neck-and-neck in national polls, in a campaign that has cost more than $2bn.

But surveys of the nine or so battleground states that will determine the election show Obama narrowly ahead.

In the crucial swing state of Ohio, a RealClearPolitics.com average of polls shows Mr Obama leading Mr Romney 49.6% to 46.6%.

The election is decided by the electoral college. Each state is given a number of electoral votes in rough proportion to its population. The candidate who wins 270 electoral votes becomes president.

A handful of governors, the entire House of Representatives and one-third of the Senate are also up for election on Tuesday.

Republicans are expected to keep control of the House, while Democrats were tipped to do the same in the Senate.