Democrats on a U.S. House of Representatives panel investigating fetal tissue procurement and practices blasted Republican leadership over reliance on discredited evidence and inadequate information sharing.

Earlier in the week, GOP members of the Select Investigative Panel on Infant Lives issued another round of subpoenas as part of an ongoing investigation that began after an anti-choice group, the Center for Medical Progress (CMP), alleged that Planned Parenthood was selling fetal tissue for profit.

The panel’s Democrats argued that their counterparts are basing their further inquiry on sources lacking credibility, in the vein of CMP and David Daleiden, who was indicted by a grand jury in Houston, Texas, in January on a felony charge of tampering with a government record.

On Tuesday, California Attorney General Kamala Harris’ office reportedly executed a search of Daleiden’s home in connection with an investigation into whether the anti-choice activist violated California law when he and associates surreptitiously recorded abortion providers in the state.

“We are increasingly concerned that, rather than following the fact-based standard that you set for this investigation, you are basing your investigation on allegations of anti-abortion extremists,” the Democrats, led by Ranking Member Jan Schakowsky (D-IL), wrote in a letter to Chairman Marsha Blackburn (R-TN).

The Democrats further alleged that Blackburn is relying on additional documentation from anti-choice groups—including a New Mexico group known as Protest ABQ—and withholding that information from the other side of the panel. Protest ABQ describes itself as “the voice of those children who are being silenced,” according to its website. In an article from February, quoted in the Democrats’ letter, Protest ABQ claims to have “submitted documentation, compiled over 5 years of research, to the panel” on fetal tissue procurement and later abortions.

In the letter, the Democrats linked Protest ABQ to Troy Newman, head of the radical anti-choice group Operation Rescue, who assisted Daleiden in establishing the now-discredited CMP. They alleged that Protest ABQ’s five-year campaign has targeted Southwestern Women’s Options, an Albuquerque-based clinic, and the University of Mexico, both of which have been subject to Republicans’ subpoenas.

“Two of your three initial unilateral subpoenas went to them, as did three of your four initial deposition demands,” the Democrats wrote to Blackburn. “Yet you have never explained why they are being targeted and have not shared with Democrats ‘documentation’ that Protest ABQ claims to have submitted to the Panel.”

They requested access to the documents and a public meeting to “explain to us—and the American people—what you are investigating and why” after House lawmakers return from recess next week.

In addition to the letter, the Democrats have launched their own website with portals to explore the benefits of fetal tissue research, access to reproductive health care, steps to improve infant health, and patients and provider safety.