Speaking in Western Michigan as part of a swing through the Rust Belt, Trump urged Whitmer to loosen restrictions on economic activity enacted to curtail the spread of coronavirus, which is surging in the region.
"You've got to get your governor to open up your state," he said to cheers. "And get your schools open."
Trump's supporters erupted into chants of "lock her up" — a refrain from the 2016 campaign originally lobbed at Hillary Clinton, but since repurposed against Whitmer and other high-profile Democrats — which Trump did little to dissuade.
"Lock "em all up," he said before pausing to soak up energy in the crowd.
The striking visual quickly came to Whitmer's attention, who responded while the president was still speaking.
"This is exactly the rhetoric that has put me, my family, and other government officials' lives in danger while we try to save the lives of our fellow Americans," she tweeted. "It needs to stop."