NASHVILLE — Education Secretary Betsy DeVos often rattles off the list of detractors standing in the way of expanding school choices for the nation’s children: the unions, the Democrats, the protesters and the bureaucrats.

But her allies and observers in the movement to overhaul education say it is time to add another to the list: her boss.

Ms. DeVos received a warm welcome here on Thursday at the 10th annual convening of center-right education reformers hosted by the Foundation for Excellence in Education, which was founded by former Gov. Jeb Bush of Florida. But despite two standing ovations for Ms. DeVos’s impassioned calls to abandon systems that she said kept students trapped in unfit or misfit schools, it was not lost on audience members that their highest-profile surrogate had returned to her constituency empty-handed. Her promised actions have gone nowhere.

The culprit, they said, is the inflammatory president Ms. DeVos works for, who paralyzed efforts at cooperation and whose language and policies are seen as antagonistic toward low-income minority communities — the very families the secretary has spent 30 years championing.