Newsweek magazine is reporting that the pro-life Santorum's wife, Karen Garver Santorum, once lived with an abortion provider 40 years her senior. Tom Allen claims his one-time lover had no problem with his chosen profession while they lived together for six years in the 1980s.
The story features an interview with Allen, a longtime Pittsburgh obstetrician and gynecologist who actually delivered Karen Garver in 1960. It includes a photograph of him cuddling with his former girlfriend, the daughter of a friend and business associate.
Allen, now 92, told Newsweek reporter Nancy Hass that his ex was "a lovely girl, very intelligent and sweet."
But there was no sign in the 1980s of the passionate pro-life crusader she would become in later years, he added.
"Karen had no problems with what I did for a living," he said.
It's not the first time the story has been reported. In a lengthy 2005 profile in a Philadelphia newspaper, Allen divulged his past out-of-wedlock love affair while dropping a bombshell that raised questions about Santorum's commitment to the pro-life cause.
"When she moved out to go be with Rick, she told me I'd like him, that he was pro-choice and a humanist," he said at the time. "But I don't think there's a humanist bone in that man's body."
The story's resurrection seven years later couldn't have come at a more inopportune time for the former Pennsylvania senator.
Santorum is duking it out with Ron Paul in a tie for third place in polls of South Carolina primary voters, according to a daily roundup of surveys by the Real Clear Politics website. Newt Gingrich is in second place and Mitt Romney is ahead of him by several percentage points.
Spouses matter to American voters, who often judge a candidate's character by his choice of marital partner. Jackie Kennedy and Laura Bush were widely regarded as having elevated their husbands in the eyes of some voters; spouses like Kitty Dukakis, Marcus Bachmann and Joan Kennedy weren't so lucky.
Spouses should matter, Santorum himself once said.
"When you look at someone to determine whether they'd be the right person for public office, look at who they lay down with at night and what they believe," he said on a campaign stop last year.
Indeed, when the country's leading evangelicals threw their support behind Santorum's candidacy over the weekend, some of them even pointed to Karen Santorum as a selling point.
James Dobson, founder of Focus on the Family, reportedly praised Karen Santorum for her decision to give up her career to raise a family; he expressed reservations, meantime, about Callista Gingrich. Participants say Dobson asked the group to consider whether Gingrich's third wife would make a suitable first lady.
In the end, the evangelicals snubbed Gingrich in favour of the man they believe represents their last, best hope to prevent Romney from winning the party's nomination — and at least partly because of Karen Santorum.
In the Newsweek article, however, those who were friendly with the former Karen Garver and her older boyfriend when they were a couple backed up the doctor's insistence that she was unconcerned about his work as an abortion practitioner and a keen advocate of reproductive rights.
One friend of the couple, Mary Greenberg, said Karen Santorum even offered to accompany her to a Pittsburgh abortion clinic in 1983.
"She told me it wasn't that bad, that I shouldn't be worried," Greenberg told Newsweek. "She was very supportive."
The couple broke up amicably in 1988 because Karen Garver wanted to have children and Allen, in his early 60s at the time and the father of adult children, had no interest in starting again. She married Santorum in 1990.
In recent remarks on abortion, her husband said he would "advocate that any doctor that performs an abortion should be criminally charged for doing so."
On the campaign trail in South Carolina late last week, however, Santorum was on the hot seat when he was asked about subsidizing abortion and Planned Parenthood, the largest provider of abortions in the United States.
"There is nobody that's been a stronger pro-life leader in the United States Congress than I was," he replied.
Karen Santorum whispered in her husband's ear soon after, reminding him about Ron Paul's opposition to anti-abortion bills in Congress.
Nonetheless, Myra Gutin, a communications professor at New Jersey's Rider University who studies first ladies, predicts Karen Santorum can easily explain away the apparent transgressions of her youth.
"He may end up expending some of his political capital trying to explain her actions, but my guess is that she says: 'You know, I was in my 20s and I grew up and I had children of my own and today, I don't feel that way anymore,'" she said Tuesday.
"It was a long time ago, and that defence would probably do the trick for her."