WASHINGTON — 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 Barack 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 (PRRI). Sixty-one percent of unaffiliated voters said they would likely cast a ballot, compared with 73 percent of those who are religiously affiliated.

The poll, one of a slew being released in the days before the election, focuses on the overlap — and sometimes contradiction — of a person's faith identity and their views on newsy topics from religious freedom to abortion.