WASHINGTON — While support for impeachment has grown steadily in the House — 136 of 235 House Democrats currently back an impeachment inquiry — the movement has also largely stalled since August, with just two Democrats backing an inquiry since lawmakers came back to the Hill in September.

Now, with new allegations that President Donald Trump used taxpayer funds to pressure Ukraine to supply dirt on one of his political opponents, this week could be the watershed moment for impeachment — or it could be the height of Democratic leadership’s ongoing timidity.

The House returns Tuesday night with massive questions to answer about Trump’s recorded conversations with Ukrainian President Volodymyr Zelensky. Trump appeared to say he discussed Ukrainian business deals that Joe Biden’s son, Hunter, was involved in.

“We don’t want our people like the vice president and his son creating to [sic] the corruption already in the Ukraine,” Trump told reporters Sunday, adding that he had discussed “all of the corruption taking place” with Zelensky in a July phone call.

But a whistleblower with knowledge of the phone call alleges that Trump tried — eight times — to pressure Zelensky’s administration into working with Trump lawyer Rudy Giuliani on an investigation into the Bidens. Conspicuously, the Trump administration held up $250 million of security aid around this same time, which they only released to the country earlier this month.

Congress wants to investigate the whistleblower’s complaint, which the intelligence Inspector General Michael Atkinson describes as “serious” and “urgent.” But Atkinson’s boss — acting Director of National Intelligence Joseph Maguire — has refused to transmit the complaint to the relevant congressional panels.

The chairman of one of those panels, Rep. Adam Schiff (D-Calif.) of the House Intelligence Committee, has requested that Maguire appear before his committee on Thursday and turn over the complaint. Maguire, however, has said he won’t show up because “he is not available on such short notice.”

Schiff has warned that his committee would subpoena Maguire, if necessary, but Democrats will have to decide whether Maguire’s refusal to cooperate Thursday will be a breaking point ― or just another moment when they back down.

Speaker Nancy Pelosi (D-Calif.) has been a consistent opponent of impeachment, advocating for a slow approach of court cases and methodical committee investigations that have thus far gone nowhere.

With such a glaring and systematic example of corruption though — the whistleblower seems to be alleging that Trump made military aid contingent on whether a foreign country would dig up political dirt on what could be the president’s election opponent — Pelosi has to decide whether her approach changes.

The speaker wrote a letter to her House colleagues on Sunday, saying that if the administration does not share the complaint, it would be “entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation.”

Perhaps the two most important words in that statement are the last: “of investigation.”

Pelosi is already signaling that Democrats will meet this moment with more of the same — investigation, not impeachment — but her caucus may be moving ahead of her.

Schiff, who has so far not supported impeachment, told CNN that he may change his mind if the administration doesn’t cooperate.

“That may be the only remedy that is co-equal to the evil that that conduct represents,” Schiff told CNN.