The re-election of Barack Obama revealed major gender, generational and racial gaps between supporters of the U.S. president and Republican rival Mitt Romney, exit polls conducted by The Associated Press suggest.

While Obama won votes from more than 90 per cent of black voters and about 70 per cent of Hispanic voters, Romney won big among white voters, taking nearly 60 per cent of that group casting ballots.

Obama lost every age group of white voters, including those 18 to 29, which he won by 10 points in 2008.

Romney, who joked at a secretly recorded fundraiser that "it would be helpful to be Latino," was the choice of less than three of 10 Hispanic voters.

Exit polls suggest big gaps in the type of voters who supported Barack Obama and Mitt Romney in the U.S. presidential election. (David Tulis/Associated Press)

"The table is set nicely for the party … because Obama did very well with Latinos, the country's fastest growing minority, and the Republicans didn't," CBC's senior Washington correspondent, Neil Macdonald, said from Obama's headquarters in Chicago. " The Republicans really have a problem with non-white voters. This is a very diverse crowd. Going forward, the Democrats are in a good position."

Obama led among women, while Romney led among men. As usual in U.S. elections, women voted in larger numbers, making up 53 per cent of the vote.

The vote also broke down over age. A majority of those under 45 voted for Obama, with people under 30 backing the president in especially large numbers. People 45 and over tended to support Romney.

Obama roused supporters during his acceptance speech by promoting America as a place where everybody is accepted.

"It doesn't matter whether you're black, or white, or Hispanic, or Asian or native American, or young, or old, or rich or poor, abled, disabled, gay or straight, you can make it here in America if you're willing to try," Obama said. "I believe we can seize this future together, because we are not as divided as our politics suggest, we're not as cynical as the pundits believe, we are greater than the sum of our individual ambitions, and we remain more than a collection of red states and blue states. We are and forever will be the United States of America."

Voter turnout drops

More generally, there was a drop in voter turnout.

Early figures from states where more than 90 per cent of the vote has been counted suggest fewer people voted this year than four years ago, when turnout records were shattered in electing Obama.

In some states, the 2012 turnout appears to be substantially lower than in 2008. And in most states, this year's numbers are shaping up to be even lower than in 2004.

The full picture won't be known for weeks. That's because so many Americans this year voted early or by mail, especially in states such as California.

The demographic breakdown comes from a survey of 26,565 voters that was conducted for The Associated Press and the television networks by Edison Research.

This includes preliminary results from interviews conducted as voters left a random sample of 350 precincts nationally Tuesday, as well as 4,408 who voted early or by absentee ballot, and were interviewed by landline or cellular telephone from Oct. 29 through Nov. 4.

Results for the full sample were subject to sampling error of plus or minus two percentage points; the margin of error is higher for subgroups.

With files from CBC News