Donald Trump has ordered a reduction in childhood vaccines — publicly faulting the shots for an increase in autism cases — even as the nation’s top health official, Robert F. Kennedy Jr., has failed to produce evidence linking vaccinations to the disorder.

While the executive order released Aug. 10 does not directly mention autism, Trump’s demand to limit vaccine recommendations has puzzled leading medical groups, doctors, and political analysts alike. The directive landed less than 90 days before midterm elections, which Trump’s own pollsters have warned could be jeopardized by anti-vaccine rhetoric.

“The political timing, particularly for members on the Republican side in swing districts, is not good,” said Larry Bucshon, a former Republican congressman and retired doctor.

Trump’s willingness to gamble on the issue underscores the president’s impatience for his health secretary to deliver on a promise that he’d pinpoint a culprit for the sharp rise in autism diagnoses.