The recent boom in religiously unaffiliated Americans may ultimately help explain the results of the upcoming 2012 presidential election, according to a new poll that shows such voters lean heavily toward President Obama but are less likely than the religiously affiliated to turn out.

Nearly one-quarter of likely Obama supporters say they have have no particular religion — a group less likely to vote than those affiliated with an organized religion, according to a poll released Monday by the Public Religion Research Institute. Sixty-one percent of unaffiliated Americans said they are certain to cast a ballot, compared with 73 percent of Americans who are religiously affiliated.