In Michigan, the secretary of state, Jocelyn Benson, a Democrat, plans to issue instructions to poll workers on what to do if they encounter threats to voters, including from self-appointed poll watchers who show up armed in a state with permissive open-carry laws.
“We are prepared,” said the Michigan attorney general, Dana Nessel, adding that every polling place will have a direct line to her office and to local law enforcement — “who can be on the ground immediately.”
With the president calling for, in his words, an “army” at the polls to “watch all the thieving and stealing and robbing they do,” Ms. Nessel, a Democrat, warned that anyone crossing the line from permitted activities to voter harassment would be charged with a felony.
“What I’d say to those listening to the president is, follow the advice of the president of the United States at your own legal peril,” she said.
The Justice Department and the F.B.I. work with local law enforcement and election officials every year to investigate allegations of fraud and of voter intimidation, but this year they are ramping up efforts to deal with threats of violence, cyber threats and other issues. Federal prosecutors have been running tabletop exercises to game out disruptions.
Nevertheless, it was notable, national security experts said, that none of the nation’s top officials from the Justice Department or the F.B.I. spoke at the news conference to announce the arrests in the Whitmer case. Mr. Trump entirely ignored the gravity of the threat against Ms. Whitmer, choosing instead to castigate her for limiting public gatherings amid the pandemic.
“I see Whitmer today, she’s complaining,” Mr. Trump said in an interview with the Fox News host Sean Hannity. “It was our Justice Department that arrested the people that she was complaining about.”