Throughout the COVID-19 pandemic, the Michigan State Capitol has been the scene of numerous protests by right-wing activists – some armed and calling for Whitmer's resignation due to the lockdown order she put in place.
At an afternoon news conference, an angry Whitmer lashed out at President Donald Trump for "stoking" hate and called the suspects "sick and depraved men."
"This should be a moment for national unity where we all pull together as Americans to meet this challenge head on with the same might and muscle that put a man on the moon," Whitmer said. "Instead our head of state has spent the past seven months denying science, ignoring his own health experts, stoking distrust and fomenting anger and giving comfort to those who spread hatred and division."
Whitmer, a frequent Trump target, said at last week's presidential debate he had offered what she called "a rallying cry" to groups she said held similar views.
"Just last week the president of the United States stood before the American people and refused to condemn white supremacists and hate groups like these two militia groups," she said, referring to suspects authorities have linked to the plot. 'Stand back and stand by,' he told them. 'Stand back and stand by.' Hate groups heard the president's words not as a rebuke but as a rallying cry, as a call to action," Whitmer said.
"When our leaders speak, their words matter. They carry weight. When our leaders meet with, encourage or fraternize with domestic terrorists they legitimize their actions and they were complicit," she continued. "When they contribute to hate speech, they are complicit."
White House press secretary Kayleigh McEnany hit back.
"President Trump has continually condemned white supremacists and all forms of hate. Governor Whitmer is sowing division by making these outlandish allegations. America stands united against hate and in support of our federal law enforcement who stopped this plot," she said in a statement.
Trump also reacted himself hours later, tweeting Thursday night that Whitmer has "done a terrible job" and, regarding the foiled kidnapping plot, "rather than say thank you, she calls me a White Supremacist."
"Governor Whitmer -- open up your state, open up your schools, and open up your churches!" he said.
In April, amid protests over pandemic restrictions, Trump faced heavy criticism for tweeting, "LIBERATE MICHIGAN!"
The FBI said it first learned of the suspects' plot in early 2020 and began embedding confidential sources and undercover agents to monitor the individuals' activities.
According to the criminal complaint, Adam Fox, Barry Croft, Ty Garbin, Kaleb Franks, Daniel Harris and Brandon Caserta started planning to take Whitmer and others hostage at the Michigan State Capitol in Lansing, Michigan.
At a news conference earlier Thursday, Andrew Birge, the U.S. Attorney for the Western District of Michigan, said that the individuals were arrested Wednesday.
"All of us standing here today want the public to know that federal and state law enforcement are committed to work them together to make sure violent extremists, never succeed with their plans, particularly when they target our duly elected leaders," Birge said.
Michigan Attorney General Dana Nessel said that seven other individuals "linked" to the militia group the Wolverine Watchmen have been charged under Michigan's anti-terrorism law.
"Our efforts uncovered elaborate plans to endanger the lives of law enforcement officers, government officials and the broader public," Nessel said.
Federal prosecutors said the militia group was already on the FBI's radar because in March 2020 they were "attempting to obtain the addresses of local law enforcement officers."
"At the time, the FBI interviewed a member of the militia group who was concerned about the group's plans to target and kill police officers, and that person agreed to become a [confidential source]," according to the complaint.
In one phone call, the complaint said, Fox said he wanted "200 men" to storm the Capitol building in Lansing to take hostages including Whitmer, and they would go on to try Whitmer for "treason."
Members of the group met, discussed and trained in their tactics regarding how they'd attack the Capitol building, including using Molotov cocktails to destroy police vehicles, prosecutors said. They also tried constructing IEDs they could use in their attack, they said.
"Fox referred to Governor Whitmer as "this tyrant [expletive]," and stated, "I don't know, boys, we gotta do something," according to a live-streamed video preserved by the FBI. "You guys link with me on our other location system, give me some ideas of what we can do."
Their plans continuously evolved over the next several weeks, according to court documents. The men suggested it might be a better plan of action to kidnap Whitmer at her vacation home or shoot it up and kill her, authorities said.
They also discussed destroying her boat, court documents also say.
During a meeting in June, the FBI says Croft and Fox and 13 others from different states gathered in Ohio to discuss violent overthrow of state governments they believed were violating the Constitution, including Michigan.
"Several members talked about murdering "tyrants" or "taking" a sitting governor," the criminal complaint filed Thursday says. "The group decided they needed to increase their numbers and encouraged each other to talk to their neighbors and spread their message. As part of that recruitment effort, Fox reached out to a Michigan based militia group."
On July 28, the complaint said, Fox posted to a private Facebook page, "We about to be busy ladies and gentlemen ... This is where the Patriot shows up. Sacrifices his time, money, blood sweat and tears ... it starts now so get [expletive] prepared!!"
In late August, Fox and a confidential source for the FBI allegedly conducted surveillance on Whitmer's vacation home, taking photographs and slow-motion video from their vehicle as they drove by the residence, authorities said.
"During the surveillance operation, Fox said, "We ain't gonna let 'em burn our [expletive] state down. I don't give a [expletive] if there's only 20 or 30 of us, dude, we'll go out there and use deadly force," the complaint said.
Later on the weekend of Sept. 12-13, the group met for a training exercise at one of their properties and constructed an IED, then all drove to the vicinity of the vacation home and Croft at one point suggested moving forward with their operation that night, court documents said.
After that weekend, the FBI says the group began to finalize their plans to kidnap Whitmer and that they all set up a meeting yesterday to "make a payment on explosives and exchange tactical gear," with the hopes of carrying out their attack before Election Day.
"Fox and Croft in particular, according to the complaint discussed detonating explosive devices to divert police from the area of the home and Fox even inspected the underside of a Michigan highway bridge for places to seed an explosive," Birge said. "The complaint further alleges that Fox purchased a taser for use in the kidnapping, and that the group successfully detonated an improvised explosive device wrapped with shrapnel to test its anti personnel capabilities."
This report was featured in the Friday, Oct. 9, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.