House conservatives long opposed to medical research using fetal tissue applied fresh pressure on the Trump administration to end government funding for such work at a hearing Thursday spotlighting antiabortion scientists who contend alternatives exist.

The hearing before subcommittees of the House Oversight and Government Reform Committee grew testy at times over whether cells from sources other than aborted fetuses are as useful as fetal tissue in advancing therapies and possible cures for diseases from HIV to cancer.

“We do not need fetal body parts from aborted babies,” said biochemist Tara Sander Lee, an associate scholar with the Charlotte Lozier Institute, the research arm of the antiabortion Susan B. Anthony List. “We never needed fetal tissue to begin with.”

The Democrats’ sole witness, Sally Temple, a neuroscientist and former president of the International Society for Stem Cell Research, countered that adult stem cells and other models “may be useful at times but cannot fully replace fetal tissues,” and warned that patients have been harmed by treatment with unproven therapies.

The hearing, which played to Republicans’ base of social and religious conservatives, comes amid moves by Trump health officials to rethink whether federal money should continue to support the research. In the past three months, the Department of Health and Human Services has severed one contract with a California firm that has been a major supplier of such tissue for laboratories. At least a few researchers’ projects are in doubt.

Administration officials emphasize that they have made no decisions and are merely examining whether alternative research models would suffice. At Thursday’s hearing, Reps. Mark Meadows (R-N.C.) and Jim Jordan (R-Ohio) said emphatically that the government should stop paying for research involving what they termed “aborted baby parts.”

The hearing reprised a 2015 controversy in which Jordan trained attention on a series of sting videos in which antiabortion activists posed as employees of a biotechnology company and secretly recorded conversations with a Planned Parenthood official.

At one point, Jordan demanded to know whether Temple, the Democrats’ witness, had ever seen the videos. She said she had.

The other Republican witness, David Prentice, the Charlotte Lozier Institute’s vice president and a cell biologist, lauded a recent paper by a University of Wisconsin postdoctoral student, which Prentice said demonstrated that discarded tissue from newborns who have had heart surgery worked as well as fetal tissue. The student, Matthew Brown, dispatched a letter to the committee Thursday, saying such claims misinterpreted and stretched his findings.

Presiding over the hearing, Meadows, the chairman of the House Freedom Caucus, repeatedly goaded Temple, asking at one point, “Why would there be a difference in charge for baby parts in the first trimester versus baby parts in the second trimester?”

“This is not my area of specialty, as you know,” replied Temple, a recipient of a MacArthur “genius” fellowship a decade ago for her work in neural stem cells.

Democrats condemned the GOP claims. “Efforts to undermine the integrity of the existing [research] framework are motivated by extreme ideology,” said Rep. Judy Chu (D-Calif.). “They do extreme harm to science.”

Meanwhile, National Institutes of Health officials say a misunderstanding prompted a recent directive to researcher Kim Hasenkrug at the NIH’s Rocky Mountain Laboratory in Montana forbidding him to procure fetal tissue that he and a collaborator need for a new experiment in their efforts to find a cure for HIV.

“There was never an intent to impede,” Lawrence Tabak, NIH’s principal deputy director, said in an interview Wednesday. In a statement Thursday, Tabak added, “We are taking steps to allow this project to resume and to avoid disruptions in other projects.”

Warner Greene, who collaborates with Hasenkrug and was the longtime director of the Gladstone Institute of Virology and Immunology, said the Montana researcher read in news accounts that NIH was offering to help him procure additional tissue, although NIH has not directly told him this.

Hasenkrug applied for additional tissue on Tuesday, Greene said, and is awaiting a reply.