House Democrats pushing for impeachment now face one of their most unusual enemies: August recess.

Beyond the usual month-long break at the end of summer, House leaders long ago set up a historically lengthy recess of almost 46 full days. After the last votes were cast Thursday, lawmakers bolted from the House and will not return until Sept. 9, leaving behind a vacuum that makes it difficult to keep up the drumbeat for beginning impeachment proceedings against President Trump.

Filling that void became more important after Wednesday’s testimony from Robert S. Mueller III landed without much drama. Democrats had spent weeks leading up to the much-hyped hearings promising that the former special counsel would provide electricity to his more than 400-page report on his investigation of Russian interference in the 2016 election and whether Trump tried to derail the inquiry.

“We want Bob Mueller to bring it to life,” House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) said Sunday on CBS’s “Face the Nation.”

Instead, the former FBI director played the part of a boring, at times halting, witness who did not want to be there.

Even Democrats who viewed Mueller’s appearances positively now think that they have to work extra hard to build public support for beginning impeachment.

Some Democrats talked about selling the sharpest moments from the testimony to constituents over the long recess. One Democrat floated the idea of returning to Washington for more hearings during August.

Another, Rep. Ted Deutch (D-Fla.), said that House committees need to quickly set the next round of hearings with Trump insiders so that there is a sense of forward momentum.

“Not just focus on what Mueller said, bring in McGahn, bring in Rosenstein, bring in Lewandowski, bring in Sessions. Let’s now fill in the dots of everything that was just explained by Mueller,” Deutch said after the House Judiciary Committee hearing Wednesday.

That lineup — former White House counsel Donald McGahn, former deputy attorney general Rod J. Rosenstein, former campaign manager Corey Lewandowski, former attorney general Jeff Sessions — contains several former Trump advisers whose testimony is locked up in assertions of executive privilege.

Those fights could end up taking several more months to resolve. The short-term reality is, given the long recess ahead, the committees investigating Trump need to put points on the board soon. That might mean scheduling hearings for September and October with lower-profile witnesses who can highlight some controversy before Trump was president, so he cannot assert executive privilege.

Their most immediate issue is how to keep the impeachment ball rolling during the next 46 days as lawmakers are spread across the nation in their districts, on vacation with their families or on official foreign travel.

Some Democrats had hoped that Mueller’s testimony would have been compelling enough to create a liberal echo to the 2009 August recess, when conservative activists flooded town halls to oppose the emerging Affordable Care Act and other large-spending items from the early days of the Obama administration.

After Wednesday, pro-impeachment Democrats think that is unlikely and instead they must make the pitch themselves, aggressively selling it to their constituents.

“I think we’ve all got to go back to our districts and answer to people,” said Rep. Jared Huffman (D-Calif.), who supports moving to impeach Trump.

He acknowledged that Mueller would not do much to change public opinion, but that lawmakers could do that themselves. “If we were waiting for the special counsel to shape public sentiment for us, that’s not very assertive leadership. We are not potted plants. We can actually shape some of this public sentiment. We’re not powerless,” he said.

House Speaker Nancy Pelosi (D-Calif.) continues to resist pressing ahead until Democrats can move public sentiment in their direction, and on that measure, the pro-impeachment crowd has a long way to go.

A Washington Post-ABC News poll earlier this month found 59 percent of Americans said the House should not begin impeachment proceedings, slightly higher than earlier this year when support ranged from 54 percent to 56 percent. Only 49 percent of Democrats “strongly” support impeachment, while 83 percent of Republicans “strongly” oppose beginning impeachment.

Pelosi, at a news conference after the two Mueller hearings, reiterated that her plan is to win in federal court and compel both testimony from Trump’s inner circle and the release of his personal financial dealings.

“We’re waiting to hear from the courts,” Pelosi told reporters.

But others fear that could take too long. Rep. David N. Cicilline (D-R.I.) suggested that if some witnesses are willing to come forward during the long summer break, committee members should be ready to fly back to Washington to hold hearings.

“I think the committee understands the urgency of the moment. I’m prepared to do whatever is necessary,” Cicilline said.

For now, the pro-impeachment Democrats did little this week to tip the scales in their favor within their own caucus. First-term Rep. Lori Trahan (Mass.), who won a 10-way primary by 122 votes last year, was the only new Democrat to join the impeachment ranks after Mueller’s testimony Wednesday.

More than three months after a redacted version of Mueller’s report was released, just 98 Democrats have publicly voiced support for impeachment proceedings, according to The Post’s whip count. That amounts to 42 percent of the Democratic caucus.

Rep. Karen Bass (D-Calif.), chairwoman of the Congressional Black Caucus, remained undecided after participating in the Judiciary Committee’s questioning of Mueller. At a town hall earlier this year, she laid out what the impeachment process was.

She says she expects her constituents to grill her about it over the recess: “Okay, you did the investigation, you had Mueller, now what?”

Rep. Donna Shalala (D-Fla.), a freshman who served in President Bill Clinton’s Cabinet, also remained undecided “I’m where I was before,” said Shalala, who found the Clinton impeachment to be a searing moment.

“I’m still, I’m patiently waiting to see if there’s a recommendation out of Judiciary and see what the speaker wants to do,” Shalala said.

Deep down, she acknowledged, she is waiting for something more compelling to help her decide. Mueller did not provide that moment.

“I need a gut check. So far I haven’t gotten anything from my gut,” she said. “I just don’t know yet.”