Trial starts for 4 men accused of plotting to kidnap Michigan Gov. Gretchen Whitmer

(CNN)Four men accused of conspiring to kidnap Michigan Gov. Gretchen Whitmer in 2020 are heading to trial with opening statements beginning Wednesday.

Adam Fox, Barry Croft, Daniel Harris and Brandon Caserta face federal charges of conspiring to kidnap the Democratic governor. Fox, Croft and Harris face additional charges of conspiring to use weapons of mass destruction including explosive devices, according to court documents. Croft and Harris are also charged with possessing destructive devices -- counts added in a second indictment last April.

All have pleaded not guilty.

The case underscores the political tensions in Michigan that reached new heights as Whitmer faced backlash for restrictions she had imposed in 2020 in response to the coronavirus pandemic. Observers have pointed to then-President Donald Trump's rhetoric toward the governor and her state, including a tweet in which he called on residents to "liberate" the state from the restrictions.

The presiding judge in the case has said the parties should avoid political discourse about hot-button current events like the 2021 attack at the US Capitol, but the defendants' alleged politically motivated involvement in anti-government activities will likely come out at trial to some extent.

The jury will see the defendants' chat messages and social media communications, photographs and video recordings of group events, and undercover audio recordings of the defendants discussing the plot, according to court documents. Two FBI agents who infiltrated the defendants' extremist group undercover are expected to testify as well.

The alleged co-conspirators, associated with a Michigan-based group called "Wolverine Watchmen," had "intended to use the destructive devices to facilitate their plot to kidnap the Governor, by harming and hindering the Governor's security detail and any responding law enforcement officers" at Whitmer's vacation home, the prosecutors said.

Fox allegedly ordered $4,000 worth of explosives from an FBI agent posing as a co-conspirator in September 2020 and Croft and Harris detonated an IED containing shrapnel near human silhouette targets "to assess its effectiveness as an anti-personnel weapon" that same day, according to the superseding indictment.

The FBI became aware of the scheme in early 2020 through a social media group.

Several other people were charged in the case by the state, in addition to those charged in federal court.