WASHINGTON – Another group of Democrats is threatening to withhold support for Nancy Pelosi as House speaker unless she backs specific rule changes aimed at fostering bipartisanship.

“We will only vote for a Speaker candidate who supports ‘Break the Gridlock’ rules changes,” nine Democrats from the Problem Solvers Caucus said in a statement Friday.

The signers, including Reps. Tom Suozzi of Long Island and Josh Gottheimer of New Jersey, want Pelosi to agree to proposals that will make it easier for bipartisan legislation and amendments to get a vote.

An aide to Pelosi said discussions with the group is continuing. The Democratic caucus is slated to vote on Pelosi’s nomination on Wednesday, while a floor vote is set for early January.

The list of demands is the latest hurdle for the nation’s first female House speaker. Last week, a separate group of 16 Democrats signed a letter vowing to vote against Pelosi, saying it’s time for change.

But one of the signers, Rep. Brian Higgins of Buffalo, reversed course after getting an agreement from Pelosi that Democrats would take up infrastructure legislation and a bill to lower Medicare eligibility to age 50.

And Pelosi also successfully convinced Rep. Marcia Fudge of Ohio to remove herself from the speaker’s race.

The rules changes from the bipartisan Problem Solvers Caucus were devised earlier this year, as frustrated Democrats were in the minority and were blocked from bringing amendments to the floor.

Incoming Rep. Alexandria Ocasio-Cortez panned the nine Democrats for seeking to impose new rules on Pelosi that the GOP majority failed to take up.

“9 Dems are choosing to hold the entire 220+ caucus hostage if we don’t accept their GOP-friendly rules that will hamstring healthcare efforts from the get-go,” tweeted Ocasio-Cortez, who backs Pelosi for speaker.

But Gottheimer said the changes aren’t pro-GOP, but pro-governing.

“The country wants us to work together again. They don’t want us to obstruct for the sake of it. They want us to try to find common ground,” Gottheimer told The Post Friday. “We still have to deal with the reality that we need to reach ideas together that will pass the Senate and the White House. We don’t control every branch of government here.”

He added: “If we are going to get to solutions on the pressing issues of healthcare, immigration and infrastructure … we’re going to have to sit down and talk to one another.”

Talks with Pelosi are expected to continue next week.

Other signers are Reps. Tom O’Halleran of Arizona, Jim Costa of California, Vicente Gonzalez of Texas, Daniel Lipinksi of Illinois, Kurt Schrader of Oregon and Florida Reps. Stephanie Murphy and Darren Soto.