The future of a federal contract with scientists who test nearly all new HIV treatments—as well as therapies for other diseases such as Parkinson’s—is in question, the Chicago Tribune reports. That’s because the research relies on fetal tissue.

Social conservatives and anti-abortionists, two groups that support the Trump presidency, claim that using fetal tissue amounts to using body parts from unborn babies and that alternatives to the research exist.

Scientists counter that the tissue comes from elective abortions and that the research has not led to an increase in abortions. What’s more, according to the Chicago Tribune, the scientists say there are no alternatives.

The investigators conducting the research in question are based at the University of California, San Francisco (UCSF). Their current research method involving fetal tissue “is absolutely essential,” stem cell researcher Irving Weissman told the newspapers. “There is no substitute today.”

It’s important to note that the UCSF group has played a role in testing nearly all HIV treatments that have been approved by the Food and Drug Administration over the decades. And the National Institutes of Health (NIH) provides the support for this research.

As such, the UCSF funding contract arrives from the NIH. Recently, UCSF researchers received a letter from the AIDS division of the NIH’s National Institute for Allergy and Diseases. Scientists expected to be notified that their contract, which amounts to a bit more than $2 million, would be renewed for another year. Instead, they were told it would continue for only 90 days. It’s unclear what will happen after that.

The Tribune reports that other federal funding has been terminated or is in question because the research includes fetal tissue.