The funding uncertainties, as well as the change that has barred second-year graduate students from applying to the fellowship, “are really eroding confidence in N.S.F. stewardship of this program,” said Gisèle Muller-Parker, a former official who directed the agency’s fellowship program from 2008 until 2017.

By law, the N.S.F. is mandated to award graduate fellowships “solely on the basis of ability,” and the program has been funding students based on the strength of their potential since 1952. But in an analysis of the 2025 awards, Dr. Muller-Parker found that a disproportionate number of fellowships went to students with research connected to A.I. and quantum information science, in line with the priorities of the Trump administration.