Despite the American obsession with voting differences between men and women - the famed U.S. election "gender gap" - there is a far bigger "gap" dividing likely voters in 2012 - the yawning divide between marrieds and unmarrieds.

Fifty-seven percent of likely voters who are unmarried support Democratic President Barack Obama in the Nov. 6 general election, including those who have never been married, live with a partner or are widowed, divorced or separated.

Thirty-three percent of those unmarried likely voters back Republican challenger Mitt Romney, giving Obama a 24-point edge among the 910 respondents, according to Reuters/Ipsos polling data for the week ended Oct. 21.

Among married likely voters, Romney led by a 13 percentage point margin, 53 percent to 40 percent, in a sample of 1,322 respondents, for a yawning 37-point "marriage gap."

"There is something that appears to be around the marriage factor alone," said Ipsos pollster Julia Clark.