A US federal judge has ordered a new trial for the two alleged ringleaders of a 2020 plot to kidnap Michigan governor Gretchen Whitmer, three months after a jury deadlocked on the charges against them, leading to a mistrial being declared.

Adam Fox, 39, and Barry Croft Jr, 46, have been charged with kidnapping conspiracy and agreeing to use a weapon of mass destruction, after they were arrested for an alleged plan to kidnap Democrat governor Ms Whitmer.

The two appealed in court on Thursday arguing that the charges against them be dismissed, but US district judge Robert Jonker denied the request and demanded a new trial instead to start “as soon as we can,” according to the Detroit News.

“A rational jury, in my view, could still rule against Mr Fox, rule against Mr Croft,” Mr Jonker said, according to Detroit News. “We will need to have another jury weigh the evidence.”

Mr Fox and Mr Croft Jr were charged in connection with the kidnapping plot along with two others — Daniel Harris, 24, and Brandon Caserta, 34 — who were cleared off the charges earlier in April by the jury that failed to reach unanimous verdicts on Mr Fox and Mr Croft.

Prosecutors said they organised a group of anti-government extremists, outraged by Covid restrictions, to execute a detailed plan that included the purchase of explosives.

The two men, who were caught after they spoke to an FBI informant and detailed their plan, allegedly said they wanted to kidnap Ms Whitmer from her vacation home and hold a “treason trial” against her over the Covid restrictions by her administration.

They also allegedly talked about raising $4,000 to buy an explosive device to blow up a bridge which would help them escape police after abducting Ms Whitmer.

Some of the men accused also allegedly held training sessions and surveilled her vacation home, according to court documents. Ultimately, the alleged co-conspirators were arrested in October 2020 during a sting operation.

Two other men indicted in the case, Ty Garbin and Kaleb Franks, have pleaded guilty, saying they hoped to spark a civil war with the kidnapping that would have somehow prevented president Joe Biden from assuming office.

Prosecutors said the men are dangerous for the society and were serious about their plan to kidnap Ms Whitmer. Defence lawyers, however, argued they were victims of federal entrapment and that undercover agents had goaded them into pursuing the alleged scheme.