Congressional Democrats have repeatedly condemned House Republicans leading a $1.59 million anti-choice investigation for withholding key documents and source information purporting to demonstrate the existence of an illicit market in “baby body parts”—a fabrication of radical abortion rights opponents.

Now, the six Democrats on the so-called Select Investigative Panel on Infant Lives are urging House Speaker Paul Ryan (R-WI) to stop what they characterized as a flagrant violation of House rules.

“For the past year, you have allowed Panel Republicans to run roughshod over House rules, notions of basic fairness, and common decency,” the Democratic lawmakers wrote Wednesday in a letter to Ryan. “As a result, they have conducted a shameful ‘investigation’ that dishonors and discredits the House.”

“The point to intervene is long overdue.”

Rep. Jan Schakowsky (IL), the panel’s top Democrat, indicated that the content of Republicans’ undisclosed documents and source information might not live up to their allegations against Planned Parenthood, abortion providers, a private company that helps procure tissue donation for medical research, and researchers who use fetal tissue to potentially cure life-threatening diseases.

“Panel Republicans have made dangerous and unsubstantiated allegations based on withheld so-called ‘evidence’ that—when revealed—does not support their inflammatory claims,” Schakowsky said in a news release.

Mike Reynard, a spokesperson for Chair Marsha Blackburn (R-TN), declined a request from Rewire for comment.

Ryan’s office did not immediately return Rewire’s press inquiries. The last time Democrats appealed to Ryan in an effort to disband the panel, he replied with a letter in June praising the investigation and Blackburn’s tactics.

The panel’s Democrats Monday released a scathing final report excoriating Blackburn and her GOP colleagues for abusing their unilateral subpoena power and otherwise shutting out Democrats, while undermining life-saving fetal tissue research, and endangering the privacy and safety of researchers and reproductive health-care providers.

Republicans are supposed to issue a final report by the end of the 114th Congress, per the resolution establishing the panel. But they have yet to indicate when they will do so, even though lawmakers are expected to leave Washington this week for the rest of the year. Republicans conceivably have until the first days of the new year to drop the report—any time before the 115th Congress convenes on January 3.

Blackburn initially publicized hundreds of pages of subpoenas, letters, and other documents, including unredacted documents that revealed researchers’ identities and linked the investigation to the Center for Medical Progress (CMP), an anti-choice front group. More recently, however, Blackburn failed to immediately disclose a request for information from Dr. Warren Hern, a prominent physician who provides later abortion care.

Blackburn remained silent on a state-level criminal referral targeting Planned Parenthood Gulf Coast. CMP’s David Daleiden and Operation Rescue, a radical anti-choice group, published blog posts last week boasting of as many as nine criminal referrals from the panel in the hours before Blackburn’s colleague Rep. Mia Love (R-UT) spoke about the referrals on the House floor. Love mentioned eight referrals in her floor speech and said more would follow.

In their letter, the panel’s Democrats reminded Ryan of Blackburn’s admission that “disclosure to Congress is not ‘public disclosure.’”

“Any alleged concern about safety risks that might flow from public disclosure does not justify withholding documents and source information from Panel Democrats,” the Democrats said. “Now, when it suits their needs, Panel Republicans have manufactured a non-existent safety concern that allows them to avoid fact checking of their alleged ‘evidence’ or allegations.”