There has been a lot of buzz recently about the wave of women running for office in 2018. It’s record-breaking. But that’s not quite right. At least, it’s too broad.

There are a lot of Democratic women signing up as candidates and winning primaries, particularly for the U.S. House. So far this cycle, according to the Center for Women and American Politics at Rutgers University, 350 Democratic women have filed to run for the House, compared with 118 Republican women. Democratic women have won 105 House primaries, compared with just 25 by Republican women.

That pattern isn’t new. The overall male skew of Congress gets a lot of attention, and rightly so, but that skew looks very different in each party. There are almost three times as many Democratic women as Republican women serving in Congress — and November’s elections might exacerbate the disparity. A Democratic wave could both send many more Democratic women to Congress and also end the careers of several Republican female incumbents.

It’s easy to understand why we are seeing more women run as Democrats than as Republicans in 2018. The combination of the election of President Trump and the defeat of Hillary Clinton, along with the women’s marches of the last two years, has created a political movement helmed by liberal women. A number of left-leaning groups are trying to help first-time candidates, particularly women, seek elective office. And if you’re a Democrat who ever wanted to run for office, male or female, 2018 is a great time to try. Republican candidates, meanwhile, are suffering from the general backlash that parties face when their president controls the White House, exacerbated by the particular unpopularity of Trump.

But this partisan gender gap isn’t just a 2018 thing. The overall gender gap in Congress is fueled and exacerbated by a more specific phenomenon: Few Republican women make it to Congress — or even run in the first place. You can’t understand — or change — Congress’s male bent without accounting for the dearth of GOP women, in particular, getting elected. And it’s not just Congress — Republican women are getting elected at lower numbers than Democratic women to state legislatures, a key stepping stone for people who eventually get to Capitol Hill.

“The Republicanism of a state’s electorate remains a strong, significant predictor of fewer women among Republican [state] legislators,” Hartwick College’s Laurel Elder wrote in an essay that was part of an anthology published this year called “The Right Women,” which chronicled the state of women in the GOP.

“This finding is stunning, as it suggests that the Republican Party itself and the increasingly conservative ideology it has come to embrace is the biggest barrier to women’s representation within the party,” she added.

Indeed, most of the progress toward gender parity in Congress that has been made over the last few decades is due to Democrats; the number of GOP women has increased, but not nearly as much.

Unless Republicans elect more women, gender parity will hit a point of diminishing returns.

So what’s going on in the Republican Party? And can it be changed? Any effort to get more Republican women elected would face hurdles almost every step of the way — from the pool of potential candidates to the primary and general elections.

There are more women in the Democratic pipeline

Hillary Clinton won 54 percent of women’s votes, compared with 41 percent for Trump, in 2016 — a similar gender gap to other recent presidential elections, according to exit polls. In other words, just in terms of raw numbers, there are probably more liberal-leaning women in the U.S. than conservative-leaning women.

Candidates, of course, are drawn from that giant pool of people. The partisan gender gap starts with more Democratic women, and it gets larger when we consider the kinds of people likely to run for Congress. Scholars have found that well-educated, highly partisan people (in both parties and of all genders) who work in high-status jobs (attorneys, for example) tend to run for Congress. Among Democrats, about half of the people with those attributes are women, while only about a fourth of Republicans with those attributes are women, according to research from political scientists Melody Crowder-Meyer and Benjamin E. Lauderdale.

Also, about half of the current Congress served at some point in a state legislature. And only 25 percent of state legislators overall are women. Here too there’s a partisan split: 36 percent of Democratic state legislators are women, compared with 17 percent of Republican state legislators.

“The gender imbalance in candidates between the parties reflects to some degree a more general imbalance in the activist populations from which candidates are frequently drawn,” said David Hopkins, a Boston College political scientist and expert on the internal dynamics of the two parties. “These days, college-educated, professional women are more likely to be Democrats than Republicans, and the Democratic Party contains female-dominated interest groups such as feminist organizations and teachers unions that help supply it with politicians and party officials.”

So the GOP starts off with fewer potential women candidates. But the lack of elected Republican women isn’t simply an unavoidable byproduct of the party’s coalition. First, the difference in candidate pools isn’t so big that it couldn’t be overcome — in terms of raw numbers, after all, there are plenty of Republican women. The real issue is the party hasn’t really tried to overcome it.

The Republican Party hasn’t made electing women a priority

The biggest difference between Democrats and Republicans when it comes to electing more women may be simple: Many Republicans don’t think that should be a goal.

“Republicans are not fans of ‘identity politics,’ and for many Republicans, that means specific, gender-based appeals,” Kristen Soltis Anderson, a Republican pollster, told me. “They want the most talented candidate, regardless of gender.”

A CNN poll from late 2017, for example, asked if the country would be “governed better or governed worse if more women were in political office?” Sixty-four percent of respondents overall said better. But there was a huge partisan split: 83 percent of Democrats said better versus just 36 percent of Republicans — 21 percent of Republicans said “worse” and 28 percent said “no difference.” A Politico/Morning Consult survey released this month found a similar pattern.

Indeed, Democrats have prioritized electing women in a way that the GOP hasn’t. The liberal group Emily’s List, for example, focuses on getting women elected at all levels of government, by encouraging women to run for office, offering them training and helping them raise money. The group, founded in 1985, is deeply enmeshed in Democratic politics, raising and spending almost $45 million in both the 2014 and 2016 elections, and pumping money into the campaigns of dozens of Democratic women currently serving in Congress.

Emily’s List has been successful, researchers say, in part because liberal-leaning women are very interested in its mission.

“Democratic women donors will prioritize electing the female candidate in a primary over other factors that traditionally predict giving,” said Michele Swers, a Georgetown University professor and scholar on women and politics. “Among Republicans, gender has no impact on donations. Republican women don’t give more to women.”

Case in point: Maggie’s List, created in 2010 as a conservative alternative to Emily’s List, raised and spent less than $210,000 in both 2014 and 2016. That Maggie’s List was formed so much later than Emily’s List and has raised so much less money is no coincidence: As Soltis Anderson pointed out, Republican activists are leery of efforts to promote specific demographic groups, including women.

The role that Emily’s List has played in convincing potential female candidates that they should run has been especially vital, according to researchers I spoke with. Surveys have found that women are less likely than men to be asked to run for political office. So leave the political system alone and it’ll skew male. Emily’s List also encourages women to run even if they have school-age children by emphasizing that women and mothers have experiences and perspectives that should be represented in the political system. It’s not clear that potential female GOP candidates are getting such encouragement.

“Running for office would take time away from what they honestly feel is the most important job they will ever do and potentially put their kids in the spotlight and the crossfire,” said GOP strategist Liz Mair, describing the thinking of some Republican women who might otherwise run for office. “And once they’re done rearing the kids, ‘stay-at-home mom’ doesn’t look like the best résumé for a potential congresswoman or senator — or at least they think that’s the case.”

In fact, Republican women may be facing some discouragement to run. In 2014, Pew Research Center asked respondents whether they would be more or less likely to support a presidential candidate who is a woman. Overall, most people (71 percent) said it wouldn’t matter. But 15 percent of Republicans and 19 percent of self-identified conservatives said “less likely” (compared with 5 percent of Democrats and 4 percent of liberals). A Morning Consult poll in 2016 found roughly the same results.

“Democrats make it easier to ‘run as a woman,’” said Corrine McConnaughy, a political science professor at George Washington University who specializes in the role of ethnicity, gender and race in politics. “That’s in large part because the Democratic Party brand/image is actually feminized to include issues that are consistent with feminine traits of compassion and nurturing — things like health care, education.”

Republican women face specific challenges in primary and general elections

But, OK, let’s say a conservative woman decides she wants to run. The hurdles don’t stop there. There are a bunch of places in the process of getting to Congress that appear to disadvantage Republican women in the context of how ideology and gender interact (even though it’s not clear that Republican women overall are less conservative than Republican men).

Moderate state legislators in both parties, men and women alike, are less likely to run for Congress than people who are more ideologically extreme, according to research by Syracuse University political scientist Danielle Thomsen. Thomsen argues that these moderate candidates are turned off from congressional service by the polarized political environment and anticipate that they will have a harder time raising money and mounting a successful campaign because party activists might prefer ideologues.

It’s not necessarily that ideologues always win the primary, Thomsen said, but that more moderate candidates don’t run in the first place because they don’t want the job, think they can’t win, or both.

Women in state legislatures in both parties tend to be more liberal than their male counterparts, according to Thomsen’s analysis of their voting records. This puts female Democrats toward the left-leaning end of their party, while female Republicans are not in the rightward bloc of the GOP. “The ideologues are much more likely to run, and they are much more likely to be men. They are really unlikely to be Republican women,” Thomsen said.

“The research I’ve done suggests that the primary campaign is the toughest hurdle for Republican women to get through, and many do not run, knowing they will not make it through the primary — where voters tend to be far more conservative than the Republican Party at large,” said Shauna Shames, a political science professor at Rutgers who specializes in studying the role of race and gender in and politics.

And even if potential female GOP candidates are as conservative as their male counterparts, voters may think they are less conservative. “There is some scholarly evidence that voters tend to perceive female politicians as more liberal than men,” Hopkins said. “This perception makes it harder for women to win votes in Republican primaries when running against male opponents, because the ideological nature of the Republican Party leads its voters to treat the relative conservatism of the candidates as an important consideration in making electoral choices.”

In fact, how much a district leans Republican has a clear effect on the chances that that district will elect a woman. All else being equal, red House districts are much more likely to elect a man.

In short, only in heavily Democratic districts do women face anything close to a level playing field. That raises an obvious chicken-and-egg question: Are Republican women choosing not to run for Congress for some of the reasons cited above? Or is the choice not to run effectively made for them, because the dynamics of the GOP make it extremely likely that they will lose, so why should they bother running in the first place?

The Republican women elected to Congress aren’t staying there

Finally, let’s say a Republican woman decided to run, got through the primary and won the general election. She is an elected member of Congress. But there still may be factors that contribute to the partisan gap in female representation. Namely, retention.

Of the 10 Republican women serving in Congress in 1991, only one remains, Rep. Ileana Ros-Lehtinen of Florida, who is retiring at the end of this year. In contrast, seven of the 24 Democratic women serving back then are still on Capitol Hill, including California’s Nancy Pelosi, who may be House speaker after the fall elections. In 2009, 21 Republican women were serving in Congress, but only nine remain, even as the majority (43 of 75) of the Democrats are still there.

“The GOP women in Congress in the 1980s and 1990s were almost all ideological moderates, and they have vanished from Congress,” Thomsen said. “The GOP women there today are an entirely new crop, whereas the Democrats have both added to and retained female members in ways that have allowed their numbers to grow.”

This retention problem is not simple. When I looked at the Republican women who have left the House since 2009, there was no obvious pattern that differed from the Democratic women who left during that time: A few of them lost their re-election campaigns; the rest chose to leave Congress after substantial tenures on Capitol Hill.

McConnaughy said the higher rates of departure for GOP women may reflect limited “upward mobility” for women in the Republican Party: The formal Republican leadership in the House and Senate has one woman (of 11 people), compared with six (of 15) on the Democratic side.

“I’m saddened that when I got here, I was the only Republican woman on the Foreign Affairs Committee, and now 26 years later, I’m still the only Republican woman on the Foreign Affairs Committee,” Ros-Lehtinen told researchers from the Rutgers center as part of a comprehensive report the center released last year on women in Congress. (The committee’s 26 Republicans now include a second woman: Ann Wagner of Missouri. Six of the committee’s 21 Democrats are women.)

Whatever the explanation, somehow erasing all impediments that GOP women face getting to Congress wouldn’t actually do much good if they’re still leaving office at a higher clip than their Democratic counterparts.

A possible path to increase GOP female representation in Congress

What will 2018 bring? More of the same, most likely — but it also may reveal a path for the Republican Party to bring more women into office.

It’s likely that the ranks of Democratic women in the House will continue to go up, simply because so many women are running and winning primaries. (It will be harder for female Democrats to make gains in the Senate, because two female senators — North Dakota’s Heidi Heitkamp and Missouri’s Claire McCaskill — are running in heavily Republican states and might lose.)

But on the GOP side, a number of the current women in the House could be defeated. Of the 68 House GOP seats considered “in play” by the nonpartisan election tracking site Inside Elections, 11 (16 percent) are held by Republican women, who hold 23 (about 10 percent) of Republicans’ total 235 House seats.

The GOP Senate landscape is somewhat more favorable to women, in part because there are some signs that the Republican establishment is practicing identity politics to some degree and making intentional efforts to promote female candidates despite the aversion to specific gender appeals by some in the party.

In deep-red Tennessee, the party has coalesced around U.S. Rep. Marsha Blackburn to replace retiring Sen. Bob Corker. Blackburn is in some ways the ideal GOP female candidate: She served in the Tennessee state legislature, has a strong conservative record and is allied with Trump on issues such as immigration. Blackburn also will be helped by Winning for Women, an initiative started last fall and backed by major male and female donors in the party that is designed to raise money and promote female GOP congressional candidates, kind of the way Emily’s List does for Democrats.

“In most cases, Republican women candidates don’t have access to a host of resources that they need, and they’re not being pushed to get out and run for office. Winning for Women hopes to remedy this,” said Andrea Bozek, a spokeswoman for the group.

Winning for Women and the party establishment also are backing Rep. Martha McSally to replace retiring Sen. Jeff Flake in Arizona. And to fill the seat of retired Mississippi Sen. Thad Cochran, Gov. Phil Bryant recently appointed Cindy Hyde-Smith, the state’s agriculture and commerce commissioner. Hyde-Smith will have to win an election this November to serve the remaining two years of Cochran’s term, but being the incumbent for a few months could help her. I don’t think Bryant picked Hyde-Smith only because of her gender, but in announcing her selection he did make sure to highlight that Hyde-Smith is the first woman ever to serve as a U.S. senator from Mississippi.

These candidacies are important because they could lay out a two-part path for Republicans to get more women into Congress. In all three cases, major figures in the Republican Party are enthusiastically and directly embracing a female candidate, as the Democrats do through groups like Emily’s List.

At the same time, it’s important that Blackburn and McSally in particular are ironclad conservatives — making it likely that they can survive a Republican primary. If so, those two and Hyde-Smith have a strong chance of winning the general election simply because they would be Republicans running in traditionally red states. This is probably the simplest way for Republicans to get more women in Congress: recruit and support strongly conservative women in red states.

This, of course, is easier said than done, for some of the reasons I laid out above: There are not that many conservative women in the pipeline to run for office; some of the party’s voters and activists may balk at intentional efforts to boost the number of female Republicans headed to Congress; and there is not yet an Emily’s List-size force on the right.

“The Republican Party is failing women and acting against its own best interests in this regard — women outvote men. It is strongly to their advantage to include more women as candidates, and it is in the country’s best interests to have women within both parties,” Shames said.

Overall, I’m not sure if a decade from now, there will be a substantially larger bloc of Republican women in Congress. In contrast, more Democratic women are running and getting elected, Democratic Party voters are majority female, and the party’s establishment is united in the goal of sending more women to Congress, so I think it’s clear that the ranks of female Democrats on Capitol Hill will continue to grow.