WASHINGTON (BLOOMBERG) - Ms Gretchen Whitmer condemned behaviour at President Donald Trump's Saturday (Oct 17) rally in Michigan, saying chants of "lock her up" from the audience, and Mr Trump's response, were "exactly the rhetoric" that's endangered her and her family.

Michigan's Democratic governor doubled down on Sunday in an appearance on NBC, calling it "incredibly disturbing" that the President is "inciting this kind of domestic terrorism".

"It's dangerous, not just for me and my family, but for public servants everywhere who are doing their jobs and trying to protect their fellow Americans," Ms Whitmer said on Meet the Press.

"People of goodwill on both sides of the aisle need to step up and call this out and bring the heat down."

Federal authorities this month charged over a dozen men in connection with a plot to violently overthrow the government of Michigan by storming the Capitol, kidnapping Ms Whitmer, and trying her for treason.

Saturday's exchange came as Mr Trump, speaking in Muskegon, escalated his criticism of the "radical left" over efforts to remove statues of historical figures linked to slavery during a rally in Michigan.

Mr Trump told supporters that one of the most important issues in his race against Democrat Joe Biden is "the radical left's plan to erase American history, purge American values and destroy the American way of life and that's what they're trying to do".

He mocked discussions about removing statues that have gained currency in recent months after nationwide protests drew attention to police brutality against people of colour.

Pivoting to the coronavirus, Mr Trump said, "You got to get your governor to open up your state."

Some of the crowd of several thousand responded with a "lock her up" chant, to which Mr Trump replied "lock 'em all up".

WHITMER RESPONSE

While the rally continued, Ms Whitmer tweeted: "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. It needs to stop."

On Sunday, Ms Lara Trump, the President's daughter-in-law and a member of his campaign team, said on CNN that Mr Trump was just "having fun" at Saturday's event.

And Mr Jason Miller, another Trump campaign official, said on Fox News Sunday that the President had no regrets about the incident.

But Ms Tori Saylor, Ms Whitmer's deputy digital director, said Mr Trump's comments have an immediate effect.

"Every single time the President does this at a rally, the violent rhetoric towards her immediately escalates on social media," Ms Saylor said on Twitter.

Mr Trump in April issued tweets urging citizens to "liberate" Michigan, Minnesota and Virginia amid lockdowns in place at the time to combat the coronavirus pandemic. All three are led by Democratic governors.

The Federal Bureau of Investigation said that the kidnapping plot identified in its criminal complaint took root prior to Mr Trump's tweets.

Mr Lee Chatfield, the Republican Speaker of the Michigan House, who also spoke at Mr Trump's rally, disavowed the "lock her up" chants.

"It was wrong," he said on Twitter. "She was literally just targeted. Let's debate differences. Let's win elections. But not that."

Mr Trump held a second rally in Janesville, Wisconsin, on Saturday night where for about 90 minutes he kept up attacks on Mr Biden and Mr Biden's family, selected Democratic lawmakers, including Representative Ilhan Omar of Minnesota, Illinois Governor J.B. Pritzker, and Ms Whitmer, again.

Mr Trump called on Wisconsin Governor Tony Evers, also a Democrat, to relax coronavirus restrictions, even as the state logs a record number of new cases.

He also hit familiar targets like members of the media including Ms Savannah Guthrie, moderator of his town hall meeting on NBC on Thursday night, and NBC's Kristen Welker, who'll moderate the Trump-Biden debate set for Oct 22.

The President flew to Las Vegas on Saturday night ahead of a rally in Carson City, Nevada, on Sunday evening.

He planned a rare visit to a church service on Sunday morning before flying to Santa Ana, California, to attend a fundraiser.