The 2018 congressional elections will give Democrats their best shot at cutting into the Republican Party’s complete control on the federal government.

But the fight over who will lead that effort — over who will be the Democrats’ standard-bearer against Donald Trump — is being waged right now in the halls of Congress.

Last week, little-known Ohio Rep. Tim Ryan announced that he’s running against Nancy Pelosi for House minority leader. It’s a long-shot bid. On Thursday, Pelosi essentially laughed off the challenge, saying that two-thirds of her caucus has already voiced support for her and that she had no doubts she’d be easily reelected. (House Democrats will vote via a secret ballot on November 30.)

But Pelosi, 76, also has some real vulnerabilities. She’s led the House Democrats since 2003 and is saddled with decades of controversial votes. She’s very unpopular in the country as a whole. Republicans have commanded the lower chamber with substantial and unbroken majorities since 2010. Under Pelosi’s watch, House Democrats again had a very disappointing Election Day — only picking up a handful of House seats, far fewer than they’d hoped.

Is this who Democrats want representing their party in 2018?

“When you get shellacked this badly, you’d normally step down,” says Joshua Huder, a congressional scholar at Georgetown, about House Democrats’ ongoing struggles under Pelosi’s tenure. “If you take this kind of drubbing, you’re out.”

Privately, some Democrats on the Hill concede that it’d be best for the Democratic Party to change directions. But they also say Pelosi is widely expected to win — in part because of the decades-long ties she has cultivated in Congress, and in part because of a critical vacuum in the party’s ranks.

House Democrats’ generational power divide

The key to understanding the battle brewing for minority leader is to first see the generational divide in the House caucus.

The House Democrats’ leadership team has been in place for a long time. Beyond Pelosi, the No. 2 and 3 Democrats in the House are Democratic Whip Steny Hoyer, 77; and Assistant Democratic Leader James Clyburn, 76.

“There really hasn’t been any young talent groomed in a way that can take over for senior leadership,” says one congressional Democratic aide, talking on the condition of anonymity to speak candidly. “We have nobody waiting in the wings.”

Below the rung of senior leadership, nearly all of the key committee positions are also filled with veteran members who have spent decades in the House. The ranking Democrat on the Rules Committee is New York Rep. Louise Slaughter, 87; on the Ways and Means Committee it’s Michigan Rep. Sandy Levin, 85; on Appropriations it’s New York Rep. Nita Lowey, 79; on Financial Services it’s California Rep. Maxine Waters, 78; and on Judiciary it’s Michigan Rep. John Conyers, 87. These are all some of the stepping stones you’d take if you were trying to climb to the upper echelons of House power.

House members do tend to be older than the public in general. But the average House Democrat is 59, according to FiveThirtyEight, and the average age of Democrats’ senior leadership is 72. (It’s just 49 for Republicans.)

This is one central fault line for understanding the upcoming Pelosi-Ryan race. In House terms, Ryan, 43, is a spring chicken. Like many of the party’s newer and generally younger members who rode to election in 2012 with President Obama’s victory, Tim Ryan has less personal attachment to Pelosi than the leaders who owe their key positions to her. (The three leaders in the House who shot down Pelosi’s rush for a quick vote on minority leader were Mass. Rep. Seth Moulton, 38; New York Rep. Kathleen Rice, 51; and Arizona Rep. Ruben Gallego, 37.)

“Our kids and grandkids are going to ask us: ‘You were in the United States Congress when Donald Trump got elected. What did you do?’ And I hope that the answer is not, ‘Nothing,’ or, ‘We thought the status quo was the direction we should have gone in,’” Ryan tells me in an interview.

But Ryan’s biggest asset — that he’s not the same person who’s been leading the Democrats for more than a decade — is also the source of his key vulnerability: He could seem woefully unprepared to assume all the complicated tasks that fall to the leader of the Democratic caucus. And that, in turn, reflects a deeper problem — just how few Democrats have serious congressional experience and are also young enough to represent a break from Pelosi’s legacy.

There’s little reason to believe this problem was intentional. As Rep. Eric Swalwell, 36, tells me in an interview, Pelosi’s team has launched several initiatives aimed at trying to help young Democrats establish themselves and move up the ranks. But the polarization of congressional districting has created a lot of safe seats, helping those with decades of experience hold on to office. It’s a legacy Democrats are still struggling to deal with.

Why some young House Democrats feel they can’t risk open rebellion against Pelosi

On their own, the junior House Democrats probably have enough votes to put one of their own in command of the caucus.

But they also have several reasons — some that reflect a genuine desire to help the party, and some that are more self-interested — for not wanting to declare an open rebellion against Pelosi.

One is that many really do genuinely regard Pelosi as a whip-smart leader who can ensure the party holds its own in vital and sometimes esoteric budget fights. In conversations with four House Democratic staffers who all expressed a general desire for a change in leadership, they all also voiced the specific concern that Tim Ryan wouldn’t have the raw talent or knowledge to do what is sometimes very complicated work — in budget negotiations with House Speaker Paul Ryan, for instance, or in strategizing how to add amendments to bills.

“Members are frustrated and want new leadership. Whoever leads the party going forward, it needs to be someone who energizes the base and taps into the grassroots, but can still bring in the money,” said one congressional Democratic aide on the condition of anonymity. “Very few believe Tim Ryan could be that person."

Another explanation is that there’s real personal loyalty for Pelosi. She is one of the most prolific fundraisers in party history, and has worked to raise millions of dollars to help rescue dozens of vulnerable House members when they needed it most. (She raised $117 million for House Democrats last cycle alone, according to Politico.) That’s bred a lot of goodwill over the years.

“Pelosi and Hoyer have been able to do a ton of favors for their membership throughout the years — they have a lot of IOUs accumulated over time,” Huder says. “So there’s going to be a lot of reticence in the caucus to betray someone who has done so much for the party.”

The last is a fear of hurting their own careers. Particularly when their party is in the minority and can’t control legislation on the floor, members crave appointment to the committees that then send bills to the full body. Especially with talk of earmarks coming back, these committees are where Democratic lawmakers will most be able to get things done that they can then brag about to their constituents. And they will likely have less of a shot at these valued slots if they’re running around launching jeremiads against a power structure controlled by Pelosi, congressional experts say.

“Having a good committee assignment is absolutely critical to whether you can be an effective representative for your district,” Huder says. “And they won’t get those if they’re actively contesting her.”

Why this could be such a bad move for Democrats

Last week, the Democratic Senate caucus cemented a foregone conclusion and made Chuck Schumer, 65, the party’s Senate Majority leader. Like Pelosi, Schumer has been around Congress for many years and isn’t particularly popular with the country overall. (Pelosi had a -25 national approval rating in the latest YouGov polling, while Schumer stands at -28.)

The two most prominent faces of Democrats in the age of Trump, in other words, are almost certainly going to be a New Yorker beloved by Wall Street and a San Francisco millionaire beloved by Silicon Valley. The GOP attack ads in the 2018 midterms will write themselves.

The strangeness of this has not been lost on either liberals or conservatives. On Thursday, Boston Globe columnist Scot Lehigh told Pelosi that “it’s time to go.” “It’s now time to give someone else a chance,” he said.

Republicans had fun needling the other party as well. On Thursday, the National Republican Conference Committee sent an email jokingly endorsing Pelosi for minority leader:

INBOX: "NRCC endorses Nancy Pelosi for minority leader" — Heather Caygle (@heatherscope) November 17, 2016

None of this appears to be making a difference. Pelosi’s claim to have two-thirds of her caucus behind her doesn’t appear to be a bluff: the Democratic aides I spoke to all thought that Pelosi is the overwhelming favorite to hold on.

And that stat that two-thirds of voters support her? That’s from Democrats calling her unprompted to voice their support — meaning that they went out of their way to tell her that they had her back, according to a senior Democratic aide.

"She's got this," the senior Democratic aide said. "There are some who are upset, but there are a handful — and I think it's a very small number.”

One theory suggested to me is that Rep. Ryan is really acting as a “stalking horse” meant to test the ground for a more serious challenge to Pelosi. Even if Ryan loses, the theory goes, he may show that Pelosi is more vulnerable than expected — if she gets less than two-thirds of the vote, for instance. That could set the stage for another, more prominent House Democrat to launch a more credible bid to her authority.

Still, it doesn’t look likely. Democrats have massive obstacles to seizing back Congress. They’ll continue to face gerrymandering that creates a natural advantage for Republicans. The 2018 Senate map is far more difficult for them than it was in 2016. Though Trump may help change that, the Democrats’ key demographic groups are typically far less likely to turn out in midterms than Republican voters.

All of that suggests the party needs to cry out for an urgent or radical change of course. For now, at least, the response is sounding more like a whimper.