President Donald Trump, who played down the coronavirus pandemic from its onset, criticised Michigan's Democratic Governor Gretchen Whitmer on Saturday for her policies to curb the outbreak, drawing shouts of "lock her up" from a rally crowd.
Mr Trump made the remarks during the first stop of a three-day trip through critical swing states, some of which he won in 2016 but that polls show are supporting Democratic rival Joe Biden this year.
The president held large rallies in Wisconsin and Michigan despite rising coronavirus cases in both states. Supporters who attended the rallies did not maintain social distancing. Some wore masks, some did not.
At a rally in Muskegon, Michigan, Mr Trump targeted Ms Whitmer several times, criticising the state’s rules to stop the spread of coronavirus, calling her “dishonest”, and making light of a right-wing plot uncovered by the FBI to kidnap her.
"They said she was threatened," Mr Trump said. "And she blamed me."
The president has been critical of Ms Whitmer, who was a candidate to be Mr Biden's vice-presidential nominee, for months.
“Hopefully you’ll be sending her packing pretty soon,” he said.
The crowd's chant of "lock her up", referring to Ms Whitmer, reprised the chants that Trump supporters often direct at former Secretary of State Hillary Clinton, who lost to Mr Trump in 2016.
Ms Whitmer responded on Twitter to the episode. "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 wrote.
Lee Chatfield, the Republican speaker of the Michigan House of Representatives, also commented on Twitter: "Trump didn’t chant 'lock her up' about our Governor. But others did and it was wrong. She was literally just targeted. Let’s debate differences. Let’s win elections. But not that."
Michigan added 1,791 new Covid-19 cases on Saturday, bringing the state's seven-day total to more than 10,000 cases, a new record, according to the state's health department.
Wisconsin reported 3,861 new Covid cases on Friday, also a new record. Mr Trump won both states four years ago but is behind Mr Biden in them this year.
Mr Biden, a former vice-president, has hammered Mr Trump for his response to the pandemic, which has killed more than 219,000 people in the United States, the highest death toll in the world. He said in a statement on Saturday that he planned to unite the country to fight the virus if he wins.
"All President Trump is offering the people of Michigan is more lies and distractions — no plan to get the virus under control, no strategy for pulling our economy out of this recession, no vision for uniting the country," Mr Biden said.
Mr Trump sought to turn that criticism around on Saturday by saying, falsely, that his rival would impede the recovery from the outbreak.
"Biden will shut down the country, delay the vaccine and prolong the pandemic," Mr Trump said at both rallies.
Mr Trump's advisers have long seen Michigan and Wisconsin, as well as Pennsylvania, as key to his chances of re-election. The president is also playing defence in traditional Republican strongholds, including Arizona, where he plans to campaign on Monday, and Georgia, where he campaigned on Friday night.
He plans to campaign in Nevada, a state Mrs Clinton won in 2016, on Sunday.