“Damaging the W.F.P. is small potatoes when you consider the much broader movement being built,” said Jonathan Westin, director of New York Communities for Change, a grass-roots organizing group. “There is a growing anger on the left about where we need to be going and that the Democratic Party has not gone there.”

Ms. Nnaemeka seemed confident of the party’s future.

“There are new formations that are aligning. The D.S.A. is growing, and there are all sorts of other insurgent left groups that we are in a deep relationship with,” she said in an interview, referring to the Democratic Socialists of America.

“We were still on an upward trajectory,” she added. “We still delivered on progressive visions even as our party changed shape.”

Bill Lipton, whom Ms. Nnaemeka is replacing, said he would be involved with the state party through the 2020 election, then work on climate issues for the national party.

The W.F.P. and the D.S.A. may not agree on everything. The W.F.P., for example, has endorsed Senator Elizabeth Warren in the Democratic presidential primary; the Democratic Socialists have endorsed Senator Bernie Sanders.

“The endorsement of Elizabeth Warren is not a choice we would have made, but everyone knows that beating Trump requires a coalition,” said Cea Weaver, a member of a D.S.A. steering committee in New York City. “We help each other be more left versions of ourselves.”