Ms. Ellis said Mr. Bauman and other Democratic leaders represented an old-school, top-down style of party leadership that had been rejected by the new wave of Democrats brought into the party by Mr. Sanders last year and by Ms. Ellis this year.

“The Democratic Party is in many ways right now where the Republican Party was when the Tea Party took over many years ago,” she said. “We are in a rebuilding moment.”

“There are a lot of things that have gone on here that have really caused folks to feel that leadership doesn’t care about them or their voices,” Ms. Ellis added. “The Democratic Party is not only changing but has changed. There are folks who haven’t gotten that memo. The way that we did things before is not going to work going forward.”

For many Democrats, what is particularly worrying is the extent to which the lingering battle illustrates the bitterness between supporters of Mr. Sanders and those of Mrs. Clinton. The California Democratic Party has seen a surge of active members since Election Day, not only in response to Mr. Trump and his policies, but also because of Mr. Sanders’s success in stirring enthusiasm.

But in some ways, these are the kind of internecine fights — be they between the old guard and new faces, or between liberals and moderates — that are common in Democratic circles, usually mainly of interest to the most inside of insiders. “Remember: We are Democrats. We do this all the time,” said Christine Pelosi, a supporter of Ms. Ellis who is the head of the California Democratic Women’s Caucus and a daughter of Representative Nancy Pelosi, the House minority leader.

But the stakes appear higher in this case. For one thing, California Democrats face a critical political challenge in 2018 as they seek to capture as many as seven Republican congressional seats, most of them in Southern California, a central part of the national party’s effort to win back Congress. California is heading into a potentially turbulent governor’s race next year as Mr. Brown — a widely respected, stabilizing force in Democratic politics — steps down after two terms. The party could also be enmeshed in a Senate race if Dianne Feinstein, who is 84, does not seek re-election next year.

The fight in this bluest of states has national repercussions for Democrats facing similar struggles about what the party should stand for — and how aggressive it should be in challenging Republicans — as it prepares for the 2018 congressional elections.

