Rick Santorum tears up ahead of Iowa caucuses. Why that's not a problem.

Time was when crying on the stump was a campaign killer, for both male and female candidates. Now, if anything, it’s a potential positive – as long as the tears are genuine.

And there was no doubting the authenticity of Rick Santorum’s emotion Tuesday at the Pizza Ranch, in Newton, Iowa, when he was asked about how he and his wife handled the death in 1996 of their son Gabriel, who was born prematurely.

A voter brought up Fox News liberal commentator Alan Colmes’s contention that the Santorums’ decision to bring Gabriel home after he died was “crazy.” The question struck a nerve. The former senator from Pennsylvania choked up as he explained that he and his wife, a former neo-natal nurse, wanted their children to meet their new brother before he was laid to rest.

“It was so important,” Santorum said, “for the family to recognize the life of that child and for the children to know they had a brother.”

His wife, Karen Santorum, stood beside him, weeping. One of their daughters came up and put her arm around her mother.

Mr. Colmes later said he apologized to the Santorums for the comment.

The episode only served to highlight Santorum’s status as a favorite among born-again Christians – a key portion of Iowa’s GOP base – in Tuesday evening’s Republican caucuses. That life begins at conception is a foundational belief among evangelicals.

Santorum, a devout Catholic, has spent more time in Iowa than any other candidate in the GOP field, often with his wife and seven children – and the effort is paying off. His late-breaking surge in polls points to a top-three finish on Tuesday – and possibly even victory.

The fact that Santorum is Catholic has not appeared to impede his rise in popularity among Iowa’s evangelicals, in a way that Mitt Romney’s Mormonism may have. More important is Santorum’s focus on family and social issues.

On Dec. 20, he was endorsed by Iowa social conservative leader Bob Vander Plaats. In 2008, Mr. Vander Plaats endorsed Mike Huckabee, that year’s come-from-behind caucus winner. On Monday, Santorum was endorsed by the Duggar family of Arkansas, famous for their 19 children, as featured on reality TV. Patriarch Jim Bob Duggar, his mother, and two of his daughters were at the Pizza Ranch in Newton with Santorum.

For Santorum, the show of emotion over the story of his stillborn son may not end up being an important part of the narrative of his Iowa caucus ride. But it certainly feeds the larger story that campaign tears, when sincere, are not the poison they used to be. Newt Gingrich shed some tears on Dec. 30 at a campaign forum, when asked about his mother. It was a one-day story.

For male candidates, in particular, the trend has been toward more discussion of family, not less. Dianne Bystrom, a political scientist at Iowa State University in Ames, found in a recent study of campaign ads that men talked about family in 18 percent of their ads, while women talked family in 8 percent.

“They’re both fighting stereotypes,” Ms. Bystrom says. “Men are trying to come across as caring and women are trying to fight the idea that they shouldn’t be in politics.”