Minnesota state Sen. Justin Eichorn (R) resigned from the legislature on Thursday in a letter read aloud on the Senate floor, as he faces federal solicitation charges.

“I must focus on personal matters at this time,” Eichorn wrote, according to the Minnesota Star Tribune. “It has been an honor to serve in the Minnesota Senate.” 

The letter was submitted to Gov. Tim Walz (DFL) via email and read on the floor by Senate Secretary Tom Bottern (DFL). Eichorn was arrested by local police on Monday in a sting operation.

Bloomington Police Department detectives communicated with the state senator to arrange a meetup with an undercover officer, whom Eichorn presumed to be a 17-year-old, authorities said. When he arrived, he was met by law enforcement and immediately arrested and booked at the jail.

“I saw your post and (sic) chance you are still available tonight?” one asked, according to an FBI affidavit, while a later message asked, “What’s a guy gota do to get with the hottest girl online tonight.”

He was charged in federal court on Wednesday. He made his first appearance on Thursday and was released on his own recognizance, according to Fox 9.

Fellow lawmakers urged Eichorn to resign after the news broke.

Democrats and Republicans were preparing to vote on his expulsion, which would be marked as the first in modern history for the North Star State.

“There is a line in the sand,” said Senate Minority Leader Mark Johnson, (R) according to the Minnesota Star Tribune. 

“If you’re accused with a felony, I think that’s serious enough — our law has distinguished that as a very serious crime. This clearly is a very serious crime, and so we are going to do the right thing as a caucus and we move forward in a very decisive way.”

Eichorn had drawn attention for co-sponsoring legislation seeking to formally label “Trump derangement syndrome” as a form of mental illness. The bill defines the condition as “the acute onset of paranoia in otherwise normal persons that is in reaction to the policies and presidencies of President Donald J. Trump.”

The Associated Press contributed.