Two of four men on trial were acquitted on Friday of conspiracy to kidnap the governor of Michigan, Gretchen Whitmer, in a plot prosecutors said was motivated by fury at the Democrat’s tough Covid-19 restrictions in the early stages of the pandemic.

The verdicts regarding Daniel Harris and Brandon Caserta were read in federal court in Grand Rapids, Michigan, US district judge Robert Jonker presiding.

Jurors said they could not agree on verdicts again Adam Fox, who prosecutors described as the ringleader of an anti-government group, and Barry Croft Jr.

A mistrial was declared, prompting prosecutors to pledge to retry Fox and Croft.

Fox, Croft and Harris faced additional charges. The two most serious, kidnapping conspiracy and conspiracy to use explosives, carry potential life sentences.

In a statement, Whitmer’s chief of staff, JoAnne Huls, said: “There must be accountability and consequences for those who commit heinous crimes. Without accountability, extremists will be emboldened.”

Defense attorneys portrayed their clients as credulous weekend warriors prone to wild talk and often high on drugs. FBI undercover agents and informants, the attorneys said, tricked the men into agreeing to a conspiracy.

Prosecutors entered evidence that the men discussed abducting Whitmer before the FBI sting began, scouting her summer home and testing explosives.

The jury was asked to figure out if the men were dangerous domestic terrorists or dupes who talked of extreme violence including hanging leaders “for treason”.

Croft is from Delaware. The others are from Michigan.

The decisions were announced a few hours after the jury said it was struggling to find unanimity on all 10 charges. The judge told jurors to keep working on a fifth day of deliberations. Jurors emerged after lunch to say they still were deadlocked on some counts.

Harris and Caserta were found not guilty of conspiracy. Harris was acquitted of charges related to explosives and a gun. Fox’s attorney, Christopher Gibbons, said the acquittals demonstrated shortcomings in the government’s case.

“We’ll be ready for another trial … We’ll eventually get what we wanted out of this, which is the truth and the justice I think Adam is entitled to,” Gibbons said.

Deliberations resumed earlier with a court employee handing over a large plastic bag containing pennies, known as exhibit 291. The pennies were requested before jurors went home on Thursday. Pennies taped to a commercial-grade firework were intended to act like shrapnel, investigators said.

According to evidence, the group detonated a homemade explosive during training in September 2020. In his closing argument on 1 April, assistant US attorney Nils Kessler said Croft wanted to test the explosive as a weapon to use against Whitmer’s security team.

Prosecutors offered testimony from undercover agents, an informant and two men who pleaded guilty to the plot. Jurors also read and heard secretly recorded conversations, violent social media posts and chat messages.

Whitmer has blamed the plotting on former president Donald Trump, for fomenting anger over coronavirus restrictions and refusing to condemn rightwing extremists.

In her statement, Huls, Whitmer’s chief of staff, said: “Today, Michiganders and Americans – especially our children – are living through the normalization of political violence. The plot to kidnap and kill a governor may seem like an anomaly. But we must be honest about what it really is: the result of violent, divisive rhetoric that is all too common across our country.”

She added: “The governor remains focused on her work on behalf of Michigan and all Michiganders. That includes addressing violence and threats to our democracy.”