The press release from the nonprofit pro-life group Cleveland Right to Life doesn’t mention Ohio Senator Rob Portman by name. It’s about updating the mission statement of one of the state’s largest pro-life groups, adding a new item to a list of practices the group rejects: abortion, euthanasia, infanticide, and...

same-sex marriage.

Wait, what? An organization whose sole focus for the past 35 years has been to put an end to abortions is now adding gay marriage to its list of things to banish?

Thank Portman, the freshman senator who until March was your typical rank-and-file conservative: pro-gun, pro-life, anti-tax, anti-regulation, anti-Obamacare, and anti–gay marriage.

That is, until Portman’s son Will came out of the closet, a year after the longtime congressman easily graduated to the U.S. Senate, winning 82 of Ohio’s 88 counties.

“He said he’d known it for some time,” Portman wrote in a column in the Columbus Dispatch, “and that his sexual orientation wasn’t something he chose; it was simply a part of who he is.”

As a candidate, Portman had campaigned as a marriage-is-between-a-man-and-a-woman kind of guy. As a newly elected senator and father of a newly out gay son, things changed.

“Knowing that my son is gay prompted me to consider the issue from another perspective: that of a dad who wants all three of his kids to lead happy, meaningful lives with the people they love, a blessing Jane and I have shared for 26 years,” Portman wrote.

Now that he had a gay child, Portman realized, “We are all children of God.”

The conservative backlash was swift.

"If his daughter was to come home and say she had just had an abortion, would there be the same change on that?" asked Molly Smith, executive director of Cleveland Right to Life, in a Cleveland Plain-Dealer analysis last month of the potential repercussions of Portman’s change of heart. "We're hoping to work with him, but we cannot possibly work with him if he does not change his view on this."

A few weeks later, Smith and her organization made the point louder, changing its very mission statement to include gay marriage as anathema. It’s just like abortion, euthanasia and infanticide, the statement reads, because it’s “contrary to the Laws of Nature and of Nature’s God.” Because “every human life is created by the sexual union of male and female” and “every child has a right to be nurtured by their mother and their father by the very nature of natural law which provides the best outcomes for the child and society,” Smith’s group will now not only fight for the rights of unborn children but also for those born to “grow up in the best and most stable environment possible... through the recognized societal contract of marriage.”

Exactly how opposing gay marriage helps children grow up in a more stable environment, the mission statement doesn’t spell out. But Smith told The Daily Beast this decision was a natural extension of Cleveland Right to Life’s core values—and a message aimed squarely at flip-floppers like Rob Portman.

The senator’s waffle was “probably a deciding factor,” she said, though the group had begun to discuss whether to broaden its scope to same-sex marriage some 18 months ago. “You can’t divorce the two things,” she said. And while her group doesn’t specifically endorse candidates, “certainly this will absolutely impact Rob Portman in the future, because of the information we will put out that he does not support our mission statement. And regardless of whether we had done this or not, our membership will not support him.”

Could backing gay marriage make Portman a one-term senator? Smith is convinced the issue has “rocked Ohio’s conservatives” and that the senator will “absolutely face a very strong primary challenge. I think it’s going to impact his funding base as well.”

Some like-minded conservatives agree. Gary Bauer is president of American Values, a Virginia nonprofit that also opposes gay marriage and abortion (and infanticide, for the record). Bauer “can’t prove it,” he says, but “I don’t think it’s a wild guess that 80 percent of the people who voted for him for senator believe marriage is between a man and a woman. If he has sufficiently stuck his finger in the eye of 5 percent of them in a highly competitive state like Ohio, if 4 to 5 percent of his vote stays home when he’s up for reelection, it’s going to be a problem.”

Bauer suggests that Portman has a credibility problem, as much as anything else. “Obviously he should love his son and support his son, but it does not follow that he should abandon the accepted definition of marriage in Western civilization for the last several thousand years.”

Does the Cleveland Right to Life’s salvo signal a looming fight for Portman with his own base in 2016, though? Not yet, anyway. Michael Gonidakis, president of the statewide Right to Life chapter made very clear in an interview with The Daily Beast Tuesday that his organization has “consistently supported Rob Portman in his career, and the senator has a 100 percent pro-life record.”

While Gonidakis called the Cleveland chapter “dear friends of ours,” he also noted that the Ohio chapter has stayed “laser-focused” over the past 40 years “on our mission to protect the unborn and end abortion. We’re Ohio Right to Life, not Ohio Right to Marriage.”

No domino effect there. While Portman may “have some explaining to do, to the people who voted for his based on his previous position,” Gonidakis said, he’s confident no primary challenger can beat the sitting senator. “I can’t even fathom it.”

Which may mean Cleveland Right to Life has stuck its neck out a little too far, said Ron Rapoport, a professor of American politics at the College of William and Mary. “Interest groups do a lot better when they stick to a single issue,” Rapoport told The Daily Beast. “I’m sure there’s overlap on this issue, but it’s certainly not total and I think it kind of weakens the movement to add on these excess issues. The Tea Party probably doesn’t have strong support for gay marriage, but I don’t think it’s a top issue for most of that group.”

An April poll by Quinnipiac University found that Ohio voters favor gay marriage 48 to 44 percent, but that Portman’s job approval rating had slipped in the wake of his statement on marriage, and Ohio is a state that passed a constitutional amendment banning same-sex marriage and civil unions by 61 percent back in 2004. (A representative from Portman's office says that the Senator's numbers have since rebounded to tie his highest levels ever in a more recent poll.)

Portman himself stayed mum this week on whether his change of stance could help or hurt his future election changes, as he has since the announcement. His spokesman emailed a list of the senator’s accomplishments in battling against abortion, touting his 100 percent score from the National Right to Life Committee in both the 112th and 113th sessions of Congress. Attached to that email was a March piece from the Columbus Dispatch, speculating not just about whether the position shift would hurt Portman’s chances of returning to the senate, but a run at the White House.

If Portman is indeed dreaming of the Oval Office, he’ll have to do that “explaining” Gonidakis speaks of all over the country, at least in the Republican primary. But come November, he’s likely to find himself neatly in line with the majority view of the American electorate. More than half of Americans polled recently support gay marriage. More than three-quarters say its nationwide legalization is inevitable.