A man upset over state-ordered coronavirus restrictions has been sentenced to just over six years in prison for planning to kidnap a Michigan Governor Gretchen Whitmer.

Ty Garbin admitted his role in the scheme weeks after his arrest last year.

His sentence on Wednesday (local time) is considered a significant break that reflected his quick decision to cooperate and help agents build cases against others.

He is among six men charged in US federal court but the only one to plead guilty so far. It was a key victory for prosecutors as they try to prove an astonishing plot against the others.

On Wednesday, Garbin apologised Ms Whitmer, who was not in court, and her family.

“I cannot even begin to imagine the amount of stress and fear her family felt because of my actions. And for that I am truly sorry,” the 25-year-old aviation mechanic told the judge.

In his plea agreement, Garbin said the six men trained at his property near Luther, Michigan, constructing a “shoot house” to resemble Ms Whitmer’s vacation home and “assaulting it with firearms”.

The government, noting Garbin’s exceptional cooperation, asked US District Judge Robert Jonker to give him credit for helping investigators reinforce their case against his co-defendants.

The “Constitution is designed to ensure that we work out our fundamental and different views peacefully, not at the point of a gun, not with some other blunt force threat or a kidnapping conspiracy”, the judge said.

Prosecutors recommended a nine-year prison term. But Judge Jonker went shorter, at six years and three months, saying he was convinced that Garbin was an “excellent prospect” to stay out of trouble when released from prison.

When the kidnapping case was filed last October, Ms Whitmer, a Democrat, pinned some blame on then-president Donald Trump, saying his refusal to denounce far-right groups had inspired extremists across the US It added even more heat to the final weeks of a tumultuous election season.

Ms Whitmer wrote a victim impact statement to the judge, saying, “things will never be the same.”

“Threats continue,” she said in June.

“I have looked out my windows and seen large groups of heavily armed people within 30 yards of my home. I have seen myself hung in effigy. Days ago at a demonstration there was a sign that called for ‘burning the witch.”‘

Last year, Ms Whitmer put major restrictions on personal movement and the economy because of COVID-19. Many limits of them have since been lifted.

The Michigan Capitol was the site of rallies, including ones with gun-toting protesters calling for the governor’s removal.

“The plots and threats against me, no matter how disturbing, could not deter me from doing everything I could to save as many lives as possible by listening to medical and health experts,” Ms Whitmer said.

“To me it is very simple: this had to be the priority.”

-AAP