Rick Santorum, a Roman Catholic, has not fared well with Catholic voters, exit polls from states that have held nominating contests show.

According to several analysts, Santorum's opposition to birth control and gay marriage could be alienating Catholic voters.

“It's not easy to describe the typical Catholic anymore,” Thomas Reese, director of the Woodstock Theological Center, a Jesuit research institute affiliated with Georgetown University, told Reuters. “We've always traditionally been the big tent that included people of all stripes.”

In Ohio, Mitt Romney, a Mormon who holds similar social conservative positions as Santorum but has kept his campaign focused on President Barack Obama, won 44 percent of the Catholic vote, while Santorum took 31 percent.

According to a recent New York Times/CBS News poll, an overwhelming majority of Catholics support gay unions. Forty-four percent surveyed favored marriage, and 25 percent said they support civil unions for gay and lesbian couples. Only 24 percent said the relationships of gay couples deserve no recognition.

Santorum has previously cited his faith in explaining his opposition to gay unions.

“Of course, the Catholic Church teaches that homosexuality is a sin. I'm a Catholic and I subscribe to the Catholic Church's teaching,” Santorum told CNN's Piers Morgan, then added: “But that's not relevant from the standpoint of how I view these issues from a public policy point of view.”