As recently as the second Reagan administration, Republicans had more women in Congress than Democrats. Then EMILY's List took hold.

The political action committee, founded in 1984, dedicated itself to electing Democratic women who support abortion rights, becoming an influential force in primaries even when it clashed with the wishes of party leaders. Now, of the 104 women in the 115th Congress, 75 percent are Democrats.

Republicans want to increase their numbers, but do they need their own version of EMILY's List to make it happen?

Some in the party think so. The GOP lacks a similar infrastructure to guide women through open primaries, instead relying on splintered, smaller groups to offer assistance — none of which carry the same weight in the Republican Party as EMILY's List does among Democrats.

Republicans, in fact, have entered the 115th Congress down one woman in the Senate and the House respectively from the previous Congress. The partisan gender gap could grow next year with multiple GOP congresswomen eyeing higher office.

"Women need to understand that there will be a network of people who will help them have the resources they need to succeed in the race," New Hampshire's Kelly Ayotte told National Journal after losing her Senate seat to Democrat Maggie Hassan in November.

Democrats and Republicans agree that EMILY's List has given Democrats a head start on electing women, but it's not clear that the PAC's model should or even could work on the right.

The EMILY's List model 

EMILY's List is driven by a litmus test — something avoided by most GOP groups dedicated to electing women.

Founder Ellen Malcolm once broached the idea of lobbying anti-abortion Democratic women in the House, but the thought was quickly dismissed at one of the organization's early steering committee meetings.

The group is only concerned with electoral politics, and it sees the pro-abortion rights litmus test as inseparable from electing women. That agenda has also been a crucial part of the PAC's success, energizing progressive donors and activists who increasingly see women's reproductive rights as a fundamental value.

"We hear from women all the time: I'm not going to vote for a woman just because she's a woman. I'm going to vote for a woman who represents my values," said Martha McKenna, former campaign director for EMILY's List.

Just as those values are now part of the Democratic mainstream, EMILY's List is a key part of the party infrastructure.

Ninety-three percent of Democratic donors had heard of EMILY's List in 2014, according to a national survey conducted as part of a Political Parity report on the main hurdles facing Republican women.

Most of the GOP groups dedicated to electing women to Congress were founded in the last decade, so they've had less time than EMILY's List to become ingrained within the party.

The lack of a litmus test among these groups helps them cast a wider net when vetting viable female candidates, but it also makes it more difficult to brand themselves and may hurt efforts to court a motivated fundraising base.

According to the same 2014 survey, 95 percent of GOP donors hadn't heard of Value in Electing Women PAC, or VIEW PAC, one of the main groups on the right that works to elect Republican women to Congress. Nearly 80 percent of GOP donors had never heard of Maggie's List, a PAC founded in 2010.

Within the sphere of conservative fiscal politics, Maggie's List makes few ideological tests. In 2016, for example, it supported moderate Minnesota Republican Darlene Miller, who was backed by members of GOP leadership, and Florida Republican Mary Thomas, who was backed by the political arm of the House Freedom Caucus. Both of them lost their primaries.

The strength of Maggie's List comes from its focus on pocketbook issues, said the group's executive director Missy Shorey.

"Social issues are used to divide us," she said.

Asked if they'd ever backed a pro-abortion rights Republican woman, Shorey said she wouldn't know because those issues never come up when the board is discussing candidates.

"Every woman's experience is her own," she said. "We don't judge."

And yet, a majority of GOP donors in 2014 were familiar with the Susan B. Anthony List, the anti-abortion group founded in 1993 with a definite social litmus test.

"There's the realization if you want to be a leader in the Republican Party, you need to be pro-life," said former Rep. Marilyn Musgrave, vice president of government affairs for the group, which unlike EMILY's List or Maggie's List, also lobbies.

It thinks of itself as the Republican EMILY's List because of its diametric litmus test on abortion rights. But whereas EMILY's List only supports women who pass their test, the Susan B. Anthony List backs men who oppose abortion rights, too. For the first time this year, it endorsed an anti-abortion man against an anti-abortion woman, helping to defeat North Carolina Rep. Renee Ellmers, one of the female Republicans not returning to the House this year.

The hesitancy on the right to organize strictly around group-based identities may stem from the GOP's traditionally more individualistic philosophy, said Rutgers professor Shauna Shames, who authored the Political Parity report.

"Somehow, the fact that I'm a woman matters more than the fact that I'm a businesswoman who creates jobs," said Shorey of Maggie's List. "That's insulting beyond words."

If fiscal issues offer the most unifying agenda to recruit and boost Republican women for Congress, there'll soon be a new fiscally minded PAC in town offering a fresh test case.

The Republican Main Street Partnership, a group of more centrist GOP members of Congress, supports moderate Republicans over tea party-backed conservative candidates. Its president, Sarah Chamberlain, is starting a new PAC with the goal of bundling early campaign money and making independent expenditures from an affiliated super PAC to help female GOP candidates.

"We also have a lot of men that are willing to fundraise to help the women," Chamberlain said, noting that men in the group were the instigators for the PAC, and that Ohio Rep. Steve Stivers, the new chairman of the National Republican Congressional Committee, is a member.

Because of its origins, Chamberlain's PAC, which grew out of a women's outreach program and which she's sold as an EMILY's List "equivalent," may have more of an ideological focus than other women's groups on the right.

"We focus more on the governing women," Chamberlain said. But it's not yet clear how the new group will endorse. "We will assess the litmus test woman by woman," she said.