Democrats are escalating calls to shut down the special House subcommittee investigating links between abortion providers and medical research involving human fetal tissue by likening the panel’s tactics to those of disgraced senator Joseph McCarthy.

During the two hearings held this year by the Select Investigative Panel, formed in October by House Republicans to probe allegations leveled in a well-publicized series of undercover videos, Democrats have invoked McCarthy’s name in decrying GOP investigators’ requests for the names of researchers and other personnel. But the comparison was amplified Friday by House Minority Leader Nancy Pelosi (D-Calif.), who appeared with more than a dozen colleagues to call for the panel’s shuttering.

“The Republicans’ … sole purpose has been to drive an outrageous campaign of misrepresentation and intimidation,” Pelosi said. “The Republicans’ Select Committee is engaged in abuses that have not been seen on Capitol Hill since the days of Joseph McCarthy.”

The comparison is a serious charge, invoking the Wisconsin Republican’s infamous pursuit of communists within the federal government between 1950 and 1954, based on what frequently turned out to be flimsy evidence, if not outright fabrication, as well as the parallel House investigation into the film industry during the same period where Hollywood figures were publicly pressured to “name names” — i.e., implicate others in wrongdoing.

“The purpose was to intimidate people from exercising their rights,” said Rep. Jerrold Nadler (D-N.Y.), a panel member, after being asked Friday to explain the parallels. “The purpose of these hearings seems to be to intimidate people — to intimidate clinics from performing abortions, to intimidate universities or clinics or anybody else from forwarding fetal tissue and to intimidate doctors from participating in any of this.”

The Democratic objections came days after the panel’s chairwoman, Rep. Marsha Blackburn (R-Tenn.), announced a new round of subpoenas targeting LeRoy Carhart, a provider of late-term abortions who has been a frequent target of antiabortion protests, some of them violent. The subpoenas appear to be trained on the 2013 death of a 29-year-old woman at Carhart’s clinic in Germantown, Md.

Maryland’s state medical examiner concluded that the woman died of a rare blood condition and did not suggest she was improperly treated at Carhart’s clinic; the state health department found “no deficiencies” in her care at the clinic, and the Maryland Board of Physicians declined to take any action against Carhart following an investigation. The Board of Physicians was among the parties subpoenaed, along with two Maryland hospitals, the Montgomery County police and fire departments, and Carhart himself.

Blackburn, in a statement, said Carhart deserved further scrutiny: “Reports regarding the Germantown clinic are deeply troubling, both for the sake of babies whose lives are ended so close to — and possibly even after — birth, and for the sake of the women who have been rushed from that clinic to the hospital with increasing frequency.”

But the Democrats, speaking Friday, said Blackburn’s decision to publicize Carhart’s name was outrageous and amounted to an intimidation campaign aimed at stifling practices that are legal under federal and state law. The criticism comes after months of tension between Republicans and Democrats on the panel over previous subpoenas that sought records from universities, hospitals and private firms involved in fetal tissue research, including names of the personnel involved in those activities.

The lists of names — which Democrats fear could be used as a target list for antiabortion extremists — has driven the most serious accusations. “We see no reason why the panel needs to amass a dangerous database of names in order to complete its work,” said Rep. Jan Schakowsky (D-Ill.), the ranking Democrat on the panel, adding that Blackburn’s “unjustified demand to name names goes beyond the bullying and abusive behavior of Senator Joe McCarthy, because she is putting people’s lives, not just their livelihoods, at risk.”

Mike Reynard, a spokesman for Blackburn, said the panel is focused on carrying out a mission that includes examining whether human fetal tissue is being sold at a profit in violation of federal law. He pointed to an April 20 panel hearing where three former Justice Department prosecutors suggested that the panel should review financial records from various parties to investigate potential violations.

“While the majority members of the Panel are busy pursuing those records, all that can be heard from the Democrats is the same old tired rhetoric designed to distract from getting to the truth,” Reynard said.

Tensions between the Republicans and Democrats on the panel have flared behind closed doors, including in private depositions. An interview of an unnamed witness this month prompted dueling letters — one from Blackburn to Schakowsky warning Democrats against creating an unofficial transcript of the deposition; the other from Schakowsky to the House clerk requesting the preservation of deposition audio recordings, citing “concerns about possible misconduct.”

Democrats also sent a five-page letter to House Speaker Paul D. Ryan (R-Wis.) on Thursday, alleging a “serious abuse of congressional power” and requesting the panel’s disbanding.

AshLee Strong, a spokeswoman for Ryan, said Monday that the speaker “supports the Select Committee’s continued efforts to protect infant lives.”