Republicans were supposed to spend the anniversary of Roe v. Wade passing a bill to restrict abortion, but instead they found themselves this week entangled in another ugly intra-party fight over rape.

A bill to ban abortion access after 20 weeks of pregnancy should have sailed through the Republican-controlled House easily. The 20-week standard polls relatively well with the American public, the House already passed a similar measure in 2013 and, in the last five years, 10 states have enacted similar laws.

But an exemption for rape victims that would have required women to file a police report to document the assault set off a very different fight. Women lawmakers said they wanted a broader exception. Other Republicans said they would vote against the bill if there was more leeway. The dispute torpedoed the bill entirely.

So while anti-abortion marchers descended on Washington by the thousands for their annual March for Life rally at the steps of the Supreme Court, instead of chalking up a victory in Congress, Republicans found themselves at a loss.

The events this week are a reminder that for all the party establishment's promises to swear off talking rape — no more Todd Akin or Richard Mourdock moments — the problem is much more than a series of rhetorical mistakes. There's a deep philosophical divide between the core of the pro-life movement, which wants no exceptions for abortion, and those who side with the vast majority of Americans, who support access to the procedure for rape victims.

The distance between these two important factions is as great as it has ever been, so Republicans are sure to find themselves debating the question of rape again and again in the context of abortion — even as the party grapples with how to win over women voters ahead of an election that could have Hillary Clinton at the top of the other ticket.

The pro-life movement is deeply divided over rape exemptions

"One of the things that's been surprising to me in studying the pro-life movement, is that there is really no support for these exemptions," says Ziad Munson, a sociologist at Lehigh University and author of The Making of Pro-Life Activists. "In all the years I've talked to people, I may have come across two or three who think its a good idea."

Anti-abortion marchers in Washington feel the same. Instead of celebrating a victory on the 42nd anniversary of Roe v. Wade, they arrived in Washington confused about why their party couldn't pass legislation they heartily supported.

"It was a disappointment," says Charmaine Yoest, president of Americans United for Life. "You had this city full of millennial activists in town for the march, who are very politically engaged, and instead of telling them 'we passed this bill,' there were just a lot of questions."

The rape issue, revisited

It might seem like the Republican party would — or should — have found a better way to discuss rape at this point. Male legislators have fumbled on the issue badly since 2012.

There was former Missouri Rep. Todd Akin's remarks, in August 2012, that women could only get pregnant from a "legitimate rape.""From what I understand from doctors [pregnancy from rape] is really rare," Akin, the Republican Senate nominee in Missouri, said at the time. "If it's a legitimate rape, the female body has ways to try to shut that whole thing down."

Then there was Indiana Senate candidate Richard Mourduck in October that year who said that when a woman conceives during a rape, "it's something God intended."

in 2013, house leadership held meeting to prevent another akin moment

Democrats seized on the gaffes to paint the Republicans as anti-women, a strategy that even President Barack Obama embraced — and beat Romney among female voters in 2012.

Republicans understood the terrible optics, and promised to change. As midterm races got underway in late 2013, House Majority Leader John Boehner's staff met with legislators and candidates expressly about avoiding Akin-esque comments.

"They’re getting out in front of the next campaign season, heading off gaffes before they’re ever uttered and risk repeating the 2012 season, when a handful of comments let Democrats paint the entire Republican Party as anti-woman," Politico reported in December 2013.

But just about a year later, Republicans find themselves in the exact same situation they hoped to avoid: on the defense over a rape-related restriction that most Americans would resoundingly oppose.

A split in opinion

Americans generally support later-term abortion bans — even those who support access to legal abortion early in the pregnancy.

The percent of Americans who think abortion should be illegal in all circumstances rises from 25 percent in the first trimester up to 80 percent in the third trimester, Gallup poll data has found.

This is what should have made the 20-week ban an easy success: it aligns with how many Americans think abortion ought to be regulated.

But rape exemptions are a different issue entirely. Most Americans think abortion should be legal in cases of rape, and the pro-life movement itself is divided on the issue.

The core pro-life movement sees rape exemptions as antithetical to their beliefs: that abortion is immoral, regardless of the circumstances surrounding the conception.

This shows up starkly in a poll that the National Right to Life Committee fielded in 2013, asking respondents about what type situations abortion ought to be legal or illegal.

Fifty-three percent of their respondents said that abortion ought to be illegal in most situations. Of those, just over half (28 percent) thought that abortion should be illegal except in cases of "rape, incest, and to save the life of the mother. The rest either thought abortion should be illegal in all circumstances (11 percent) or legal only to save the life of the mother (14 percent).

"The argument is that the conditions surrounding the conception are not morally relevant," Munson says. "So they would say that, yes, its unfortunate that a rape happened, but that's not the child's fault."

That's the view that Kristina Hawkins, president of Students for Life, expressed talking about the House bill on Thursday. "I'm not in favor of abortion in any situation," she said. "I would like to see bills that don't have rape exemptions. I know, pragmatically, some feel you have to moderate, but I don't really agree with that."

Or, as Brandi Swindell, a pro-life activist from Idaho who attended March for Life Thursday put, it "Our position is that we are 100 percent pro-life without exception."

That puts her at odds with Yoest at AUL, the country's oldest pro-life group, which helps state legislators draft anti-abortion laws. She says that her team will work with lawmakers to insert rape exemptions that can respond to where the larger electorate — and not just pro-life activists — stand on the issue.

She expects House leadership to revisit the 20-week ban later this year, and ultimately pass it — although was unsure how the language regarding the rape exemption would ultimately shake out.

"Sometimes it's the political world we live in," she says. "You look at how you're going to put a bill together based on what the surrounding circumstances are."