Democratic frustrations with the House majority’s oversight of President Trump are beginning to boil over, as longtime party strategists and liberals alike decry what they view as an ineffective effort to hold a lawless president accountable.

In more than seven months of investigating Trump, a half-dozen Democratic-led House committees have struggled to unearth major findings, hold high-profile hearings that move public sentiment or follow up on inquiries they laid out when the party took the majority in January. 

The thin record increases the pressure on Democrats for Wednesday’s hearings with a long-sought witness, former special counsel Robert S. Mueller III, who will answer questions about his nearly two-year investigation into Russian interference in the 2016 election and whether Trump tried to derail the inquiry.

Investigators blame Trump’s historic stonewalling for their difficulties. The administration is blocking more than 20 congressional investigations, according to a Washington Post analysis, and has instructed current and former aides or Trump-related entities to ignore at least half a dozen subpoenas. Democrats are litigating three subpoenas in court, including compulsory measures for Trump’s bank and financial lenders, as well as his tax returns.

But the lack of action — or a clear strategy — is starting to rankle Democrats, as the House leaves for a six-week recess Friday.

Two of the committee chairmen leading investigations — Judiciary’s Jerrold Nadler (D-N.Y.) and Ways and Means’ Richard E. Neal (D-Mass.) — have drawn primary challengers who dismiss glacial-paced oversight and demand the ultimate step: impeachment proceedings against Trump.

“There’s a lack of urgency,” said Alex Morse, 30, the mayor of Holyoke, Mass., who announced Monday that he would challenge Neal. The 16-term congressman “hasn’t fully used the power that he has” to stand up to Trump, said Morse, adding: “We’re setting an incredibly dangerous precedent if we don’t [impeach] . . . If not for this president, then for what president, ever?”

Morse said he would hold Neal accountable for a slow-walking probe of Trump’s tax returns after it took months for the senior Democrat to file a lawsuit in hopes of obtaining the documents. The administration has refused to cooperate.

The bitterness is expressed by party challengers and far-left groups, but it extends beyond the most liberal voices. A core group of aides to President Barack Obama who dealt with relentless GOP investigations of their former boss have questioned whether House Speaker Nancy Pelosi’s aversion to impeachment has created what Dan Pfeiffer, a former senior adviser to Obama, recently called a “bizarre abdication” of congressional duties. 

The frustration with Pelosi (D-Calif.) and the oversight strategy was on full display during a mid-July “Pod Save America” podcast with Pfeiffer and Jon Favreau, a speechwriter for the ex-president. Pfeiffer railed about Pelosi’s refusal to investigate now-resigned Labor Secretary Alexander Acosta for the generous deal he once offered registered sex offender Jeffrey Epstein.

“Congressional oversight is not an option . . . it is their job,” Pfeiffer said, arguing that Pelosi has “put herself in a maximum-security prison of political caution,” working backward from an end goal of avoiding impeachment rather than letting the facts lead where they may. “I’m really losing patience.”

“She has trapped herself, she has backed herself into a corner by every day seeming to close the door on impeaching Donald Trump, so that every other investigative question, every other potential scandal . . . she starts worrying that if she goes down that road, it leads to impeachment, which she doesn’t want to do,” Favreau agreed. “Why do any investigations or oversight at all if it’s not possible that what you uncover would lead you to impeach the president? ”

Pelosi’s office in a statement flatly rejected the notion that Democrats aren’t doing enough to hold Trump accountable. Spokeswoman Ashley Etienne said that “much of what is now known about the Trump Administration’s corruption, incompetence and cruelty was exposed by House Democrats’ investigations and persistent oversight work.”

“With the power of the majority, Democrats are legislating, investigating and litigating,” she said. “Successfully holding the Trump Administration accountable requires meticulous, strategic and relentless work to build an ironclad case that wins in the courts and wins with the American people.”

Outside critics complain that the Judiciary panel has done little to try to force witnesses in Mueller’s report to testify. Former White House counsel Donald McGahn ignored one subpoena to appear two months ago, but Democrats have yet to take him to court or subpoena any others for public testimony.

“It feels a bit like ‘Whac-A-Mole,’ ” said Ben LaBolt, a former Obama spokesman who oversaw the president’s response to GOP probes. “A bunch of one-off hearings on different topics is not going to lead to progress on any of these issues, and it’s not going to break through in the news cycle, so they’ve got to home in on a limited set of topics repeatedly.”

In their defense, Democratic investigators say the process takes time. If they rush to court, aides and lawmakers on the panels have repeatedly said, they could lose; better to bring an airtight case, they say. 

The congressional oversight process rarely fulfills the rapid-fire demands of some Democrats.

“We’re in an environment right now where people’s expectations for what oversight can do are really mismatched with what it’s designed to do,” said Andy Wright, a former Obama counsel who also has worked on the House Oversight and Reform Committee. Democrats, he said, are “seeding the groundwork for further information to come to light later on, whether it be in court or in [Government Accountability Office] reports or [inspector general] referrals or their own subpoenas ultimately getting enforced . . . It’s just not going to work at the pace where I think people have been setting benchmarks of success in their minds.”

Democratic calls for more aggressive oversight come amid relatively stable polling on impeachment. A July Post-ABC poll found that 37 percent of Americans support Congress beginning impeachment proceedings, while 59 percent do not, with a 61 percent majority of Democrats backing proceedings. A January Post-ABC poll found similar shares of both Americans overall (40 percent) and Democrats (64 percent) in favor of impeachment proceedings. 

Democratic skeptics of the oversight strategy, however, say that even if the majority of voters don’t support impeachment, the House has a responsibility to aggressively investigate Trump.

“The entire approach toward the administration from House Democrats has been one of weakness and fecklessness — and not the kind of fighters that people were hoping would come out when they were voting for Democrats last November,” said Ezra Levin, a co-executive director for Indivisible, a political resistance group. “They have made a strategic choice — thus far, at least — to not fight on oversight.”

To be sure, Democrats have had some successes. The House Oversight Committee has shined a spotlight on Trump officials’ attempts to sell nuclear technology to Saudi Arabia. It has also illuminated problems in the security clearance process, with one whistleblower coming forward to claim that Trump was putting the nation’s closest-held secrets in jeopardy.

The list of untouched or stalled House investigations has grown. After Trump’s former personal attorney Michael Cohen testified in February about hush payments made to women during the 2016 campaign, Democratic investigators promised to question Trump Organization Chief Financial Officer Allen Weisselberg and even Donald Trump Jr., whose signatures were scribbled on copies of the checks given to the women alleging affairs with Trump. There have been few announcements about that probe since then.

The same is true regarding Trump’s meetings with Russian President Vladi­mir Putin. Democrats sought the translator notes Trump seized but have not issued a subpoena for the material. Investigators haven’t launched a probe into Ivanka Trump’s business dealings that may have benefited from her time in the White House, particularly working with Chinese’s officials. And there’s been little congressional action on an inquiry into whether President Trump illegally profited from foreign and state government visitors at his luxury hotel in downtown Washington — though that matter is mired in the courts.

At the same time, some of the oversight moves seem scattershot, according to some Democrats and Republicans. In March, Nadler sent 81 letters to Trump associates demanding all communications related to a host of controversies surrounding the president.

In July, Nadler issued new subpoenas for a dozen Trump contacts who played major roles in the Mueller report.

“The last six months of this committee reminds me of my kids: I can track them from place to place by the trail of toys they leave behind: We’ve got 81 fruitless letters, unnecessary subpoenas, empty chairs and buckets of chicken,” said Rep. Douglas A. Collins (Ga.), the top Republican on the Judiciary panel, knocking Democrats for appearing to have no strategy in their investigations.

Officials for the Judiciary Committee had no comment. Nadler, however, said weeks ago that he wanted to move to court immediately to force McGahn’s compliance and has privately pushed leaders to move faster.

Nadler is now facing three primary challengers, including one, Lindsey Boylan, who raised more than $250,000 in the last quarter and has made Nadler’s Judiciary work central to her campaign against him.

“By refusing to impeach Trump, Democratic leaders are violating their oath to defend our Constitution,” Boylan, a former aide to New York Gov. Andrew M. Cuomo (D), wrote on Facebook in a new push to highlight his refusal to initiate impeachment proceedings. “Join me in calling on my NY-10 opponent, Rep. Jerry Nadler, to exercise his authority and stop hiding behind Speaker Pelosi.”

David Weigel contributed to this report.