MICHIGAN Governor Gretchen Whitmer has accused US President Donald Trump of issuing a “rallying cry” to extremists after police foiled a plot to kidnap her.

Six men have been charged over the plot to abduct Ms Whitmer, a Democrat, and hold a mock “treason trial” that would put her to death for imposing lockdown restrictions due to coronavirus.

Ms Whitmer pointed to Mr Trump’s presidential debate instruction to the white supremacist Proud Boys to “stand back and stand by,” saying “hate groups heard the president’s words not as a rebuke, but as a rallying cry... when our leaders meet, encourage or fraternise with domestic terrorists, they legitimise their actions.”

Democratic presidential candidate Joe Biden pointed to the president’s tweet earlier in the year in which he called on unspecified persons to “liberate Michigan” because of Ms Whitmer’s lockdown restrictions as encouraging plots against her.

However Mr Trump said that Ms Whitmer had done a “terrible job,” should lift all coronavirus restrictions and that what he called “my” federal law enforcement agencies had thwarted the plot, adding: “Rather than say thank you, she calls me a white supremacist.”

Democrats began proceedings today to invoke the US constitution’s 25th amendment to challenge Mr Trump’s fitness for office based on his health, on the basis of a series of bizarre tweets he has issued in which he bragged of being “a perfect physical specimen” and “very young.” Mr Trump is 74.

But the president hit back, saying: “Crazy Nancy” (Pelosi, the House Speaker and a Democrat) “is the one who should be under observation. They don’t call her crazy for nothing!”

He also took aim at Black Lives Matter demonstrators, saying that Democrats were encouraging “looters and mobs to burn down” US cities.

The mother and sisters of a black teenager killed by police in Milwaukee were arrested on Thursday during a protest against his killing.

Alvin Cole, 17, was shot dead in February. Police say he fired at them first.

His mother Tracy and sisters Taleavia and Tristiana were arrested alongside others. Their lawyer Kimberley Motley said they were detained “for peacefully protesting.” Tracy and Tristiana Cole both had to be taken to hospital after their encounters with police. 

A Facebook livestream of the arrest records Tracy Cole shouting: “I can’t believe y’all did this to me. Y’all killed my son.”