WASHINGTON USA (AP) — President Barack Obama won the reliably Democratic Northeast, and Republican Mitt Romney secured his Republican conservative base Tuesday night in a tense duel for the White House shadowed by a weak economy and high unemployment.

The critical battlegrounds with the key to victory were unsettled – Virginia, Ohio and Florida among them – with long lines in many locations after poll-close time.

Romney led in the national popular vote with 13 million votes, or 51 per cent, to 12 million or 47 percent for Obama, with 10 per cent of the precincts tallied.

Romney also held an early electoral vote advantage, 147-123, with 270 needed for victory, although he lost both his home state of Michigan and Massachusetts, where he served one term as governor.

The economy was rated the top issue by about 60 per cent of voters surveyed as they left their polling places, but more said former President George W Bush bears responsibility for current circumstances than Obama does after nearly four years in office.

About four in 10 said the economy is on the mend, but more than that said it was stagnant or getting worse more than four years after the near-collapse of 2008. The survey was conducted for The Associated Press and a group of television networks.

Polls were still open in much of the country as the two rivals began claiming the spoils of a brawl of an election in a year in which the struggling economy put a crimp in the middle class dreams of millions.