Nancy Pelosi won another term as the House Democratic leader on Wednesday, beating back a symbolic challenge from Ohio Rep. Tim Ryan. It was the umpteenth proof point of a very simple fact that anyone who knows Congress has been aware of for quite a while now: Nancy Pelosi can't be beaten. The only way she will exit Democratic leadership is if and when she decides she has had enough.

The reasons for Pelosi's dominance are simple.

1. House Democrats are much more liberal than they were a decade ago. Although Ryan made much of Democrats' electoral track record in the recent election — the 2010 and 2014 midterms in particular — the practical result of all of the losses the party sustained was actually to strengthen rather than weaken Pelosi's hold on power. Why? Because the vast majority of Democrats who lost in those wave elections were in the moderate-to-conservative wing of the Democratic Party. That means that the relative percentage of liberals within House Democratic ranks has soared over these past few elections. And Pelosi is strong as hell among that liberal wing.

2. Pelosi is a huge fundraiser. Nothing breeds loyalty in politics like campaign dollars. And no one outside of Barack Obama and Hillary Clinton has proved more adept at raising huge sums of cash for Democratic causes than Pelosi. In the 2016 election alone, she raked in more than $40 million — three-quarters of which she raised directly for the House Democratic campaign arm. Since she was elected to leadership in 2002, Pelosi has raised almost $470 million, according to figures provided to Politico. Pelosi — and her allies — have long made the case that no other person inside the caucus could come anywhere near those sums, leaving the party underfunded if she walked away.

3. The rest of leadership offers zero contrast to her. The strongest argument against Pelosi is that it is time for a change, time to let the younger guard take over the party. But that argument is best made by someone already in or close to leadership — not a relative unknown like Ryan or, in 2010, then-Rep. Heath Shuler (N.C.). Of course, that younger voice does not exist in the current incarnation of House Democratic leadership. Reps. Steny H. Hoyer (Md.) and James E. Clyburn (S.C.), the next two highest-ranked House Democrats, are 77 and 76, respectively. (Pelosi is 76.) Hoyer has been in Congress since 1981, and Clyburn has held his seat since 1992. (Pelosi was first elected to the House in 1987.)

She just is not going to lose. If she stands for leadership, she wins. That may well not be a very good thing for the party that she has helped lead over the past decade-plus.

What Democrats did Wednesday is change absolutely nothing in the face of a(nother) disappointing election result. The party has lost almost 1 in every 5 House seats it held after the 2008 election — but it has kept the same team in place.

If you are a rank-and-file House Democrat (or really any Democrat not in leadership), that's not exactly the most encouraging sign about the future of the party. Win or lose, the leaders stay the leaders. Meanwhile, on the other side of the aisle, the leaders are not only young — Speaker Paul D. Ryan (Wis.) is 46, Majority Leader Kevin McCarthy (Calif.) and Majority Whip Steve Scalise (La.) are both 51 — but relatively new to their jobs. (Obviously the process that led to the leadership overhaul for Republicans was decidedly messy.)

The unwillingness of Pelosi, Hoyer and Clyburn to step aside has already had a huge effect on the next generation of leaders. Sen.-elect Chris Van Hollen (Md.) got tired of waiting around. Ditto Rep. Steve Israel (N.Y.), who retired in 2015. Rep. Debbie Wasserman Schultz (Fla.) did herself in with her rocky tenure at the Democratic National Committee. Rep. Xavier Becerra (Calif.) is Pelosi's groomed heir apparent, but it's unclear whether that status is worth as much as it once was.

Power rarely relinquishes power willingly. If you are Pelosi and you believe that (a) you are the one necessary and irreplaceable cog for House Democrats and (b) you can't be beaten in a caucus-wide vote, there is not a tremendous incentive (or really any) to step aside. Ditto Hoyer and Clyburn, who enjoy the privileges and profile that come with being in leadership.

But it's hard to argue that the correct response, politically speaking, to what has happened to congressional Democrats over the past decade is to do nothing and change nothing. Hillary Clinton's stunning loss exposed the party's decidedly thin bench of future stars. But at least it also cleared the way for those young and ambitious pols to make a run for the big office. Pelosi's reelection — coupled with the return of Hoyer and Clyburn — effectively blocks any real paths for those same sort of ambitious politicians in the House.

And that's a bad thing for a party that finds itself at a remarkably low ebb nationally.