Maine’s Gov. John Baldacci is one of at least 30 U.S. governors to receive an anonymous letter demanding their resignation.

Spokesman David Farmer said the governor received the letter Monday and it was passed on to his executive security detail which is working with the FBI.

“Believe it or not we get a lot of oddball mail. This is not unusual in that regard,” Farmer said. “We have to take these things seriously.”

What Farmer described as a manifesto was about a half-inch thick stack of documents that looked like legal paperwork sent on behalf of the “De jure Grand Jury.”

The letter declared that the era of illicit corporations and banking cartels posing as legitimate governments is over, he said.

According to the Associated Press, a federal intelligence note is warning police that an anti-government group’s call to remove dozens of sitting governors may encourage others to act out violently.

A group that calls itself the Guardians of the free Republics wants to “restore America” by peacefully dismantling parts of the government, according to its Web site.

As of Wednesday, more than 30 governors had received letters demanding they leave office within three days or they will be removed, according to an internal intelligence note by the FBI and the Department of Homeland Security, which was obtained by The Associated Press.

Investigators do not see threats of violence in the group’s message, but fear the broad call for removing top state officials could inspire others to act out violently.