A Christian conservative has described Ohio Senator Rob Portman's support for gay marriage as ending his career.

In March, Portman announced in an op-ed that he had reversed course on the issue of marriage equality and credited his son's recent coming out for the change of heart. The announcement made Portman, who faces voters in 2016, the only Senate Republican to publicly endorse the institution. Since then, Illinois Senator Mark Kirk, also a Republican, endorsed marriage equality.

Phil Burress, who heads the Cincinnati-based Citizens for Community Values (CCV), told the Cleveland Plain Dealer that Portman's “career is over” in 2016.

“This is a policy with the pro-family movement, not just us,” Burress said. “There's two non-negotiable issues: abortion and marriage, or the 'homosexual agenda.' And if you're wrong on either one of those, [we] will campaign against you and we will defeat you.”

Other leaders appeared to agree that the issue would hurt Portman, at least among social conservatives.

“I can't tell the future on this, but I don't see how it could be just a blip,” said Gary Bauer, president of of the Virginia-based American Values. “And I guess one way to look at it would be if a Democratic senator ran promising the gay rights movement that he would be in favor of same-sex marriage and then got into office and reversed on that. Would the gay-rights movement say to him, 'Oh, that's OK we notice you've also been voting pro-choice and against gun rights?'”