Women make up a fifth of Congress. Strategists from both parties would like to see that percentage increase in the 2018 midterms, but that’s no guarantee.

Eleven women have announced they’re leaving the House at the end of this term, including two Democrats and one Republican who are running for Senate. Arizona Rep. Martha McSally could make it a second Republican if she jumps into the open Arizona Senate race. Three female Democrats are among the top 10 most vulnerable senators.

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Both parties have female members who’ve made it their priority to recruit and mentor female candidates. For the first time ever, the National Republican Congressional Committee’s recruitment head is a woman.

But Democrats dominate when it comes to female representation. Of the 21 women in the Senate, 16 are Democrats. Of the 84 voting women in the House, 62 are Democrats.

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EMILY’s List, which backs female Democrats who support abortion rights, boasts that so far this year more than 20,000 women have approached the group about running for all levels of public office. That doesn’t mean all of them will run, and it certainly doesn’t mean they’ll run for Congress. But it’s a notable figure given that only 920 women approached the group about running during the entire 2016 cycle. More women — mostly Democrats — are making political donations this year, too.

EMILY’s List is a major powerhouse in the Democratic Party, often choosing sides in primaries, even when it goes up against leadership. But this year has seen an intraparty debate about the merits of an abortion rights litmus test, with opponents concerned that anti-abortion recruits — who could be good messengers for Democratic economic values in more conservative areas — have no home.

As recently as the second administration of President Ronald Reagan, there were more Republican than Democratic women in Congress. Coming onto the scene in the 1980s, EMILY’s List changed the balance dramatically. Without a comparable group on the right, Republicans have struggled to convince women to run, and where they’ve landed female recruits, they’ve struggled to get them through primaries.

The GOP groups that recruit and support female candidates have typically been splintered on the right. Most don’t have a litmus test, especially not on social issues. That can make it harder to energize donors and the base. Republicans are uniting around a new effort, led by megadonor Paul Singer, to help elect women next year.

And they’re not without recruits. So far, strategists are excited about a dozen House candidates who are expected to mount serious campaigns this cycle. But with a quarter of the GOP women in the House having already announced they’re not returning in 2019, it remains to be seen if the party can make up that loss.