Abortion was discussed only briefly during Thursday night’s vice-presidential debate, but the exchange about it was, I think, an important moment, because it drove home the likelihood than a Republican victory in November will mean the end of Roe v. Wade.

In the last week, as Mitt Romney has cultivated a new, more moderate image, it looked like he was having some success catching up to President Obama among female voters. Neither reproductive rights nor equal pay figured in the first presidential debate, which almost everyone agrees that Romney won. When it was over, Romney continued his lurch to the center. Contradicting everything he said in the primary, he told an Iowa newspaper that he knew of “no legislation with regards to abortion that I’m familiar with that would become part of my agenda.” While his spokeswoman walked it back, conservatives, happy that Romney finally seemed to be winning, didn’t demand any loud mea culpas. A person paying only sporadic attention to the campaign probably wouldn’t realize that Romney has pledged to work toward a wide-ranging abortion ban.

During the vice-presidential debate, many pro-choice observers were irritated by the way moderator Martha Raddatz framed her lone question about abortion in terms of the candidates’ Catholicism. “Please, let’s hear more from two religiously observant white men about their personal experiences with women’s reproductive freedom and access!” wrote Salon’s Irin Carmon. “It’s not that religion, or men, have no place in the debate over abortion rights; it’s that her question left women out of the equation from the start.” She has a point. Catholicism, after all, also has plenty to say on issues like war and poverty, but only when it comes to women’s rights is it considered acceptable for politicians to let personal theology dictate grave policy questions.

Nevertheless, the question worked perfectly for Joe Biden. In general, Americans are ambivalent about abortion, but they don’t want to make it illegal. By speaking in religious terms, Biden was able to combine his personal opposition to abortion with a strongly pro-choice stance. In his own life, he says, he accepts Catholic doctrine. “But I refuse to impose it on equally devout Christians and Muslims and Jews, and I just refuse to impose that on others. Unlike my friend here, the congressman, I do not believe that we have a right to tell other people that—women they can’t control their body. It’s a decision between them and their doctor.”

Ryan, by contrast, reminded the country that he opposes abortion in all circumstances, and that Romney intends to severely restrict it. “[I]f you believe that life begins at conception … That’s a principle,” he said. “The policy of a Romney administration is to oppose abortion with exceptions for rape, incest, and life of the mother.” When Raddatz asked him if abortion-rights supporters should fear a Romney administration, he sort of harrumphed, and then responded, “We don’t think that unelected judges should make this decision; that people through their elected representatives in reaching a consensus in society through the democratic process should make this determination.” In other words, they want to overturn Roe.

During every presidential election I can remember, pro-choice groups have worked hard to remind female voters that Roe is at stake, while Republican candidates have tried not to say anything to scare them. George W. Bush, remember, rarely spoke about banning abortion—he talked about promoting a “culture of life.” But Ryan was admirably clear about his ticket’s intentions. None of this, of course, will be news to those who have followed the campaign closely. In general, though, swing voters haven’t been. It will be interesting to see whether women start moving back away from Romney after hearing what he and Ryan have in store.