The AIDS epidemic has killed more than 40 million people since the first recorded cases in 1981, tripling child mortality and carving decades off life expectancy in the hardest-hit areas of Africa, where the cost of treatment put it out of reach. Horrified, then-President George W. Bush and the U.S. Congress two decades ago created what is described as the largest commitment by any nation to combat a single disease.

The program, known as the U.S. President’s Emergency Plan for AIDS Relief, or PEPFAR, partners with nonprofit groups to provide HIV/AIDS medication to millions around the world. It strengthens local and national health care systems, cares for children orphaned by AIDS and provides job training for people at risk.

Now, a few Republican lawmakers are endangering the stability of the program, which officials say has saved 25 million lives in 55 countries from Ukraine to Brazil to Indonesia. That includes the lives of 5.5 million infants born HIV-free.