A Republican state senator in Minnesota was arrested this week and accused of arranging to meet with an underage prostitute, the police said, making him the second lawmaker in the closely divided State Senate to now be facing felony charges.

The Republican senator, Justin Eichorn, 40, had actually been talking to a detective from the Bloomington Police Department in Bloomington, Minn., who was posing as a 17-year-old when he arranged the meet-up on Monday, the police said.

The authorities are recommending that he be charged with soliciting a prostitute under the age of 18, a felony that is punishable with up to five years in prison.

Mr. Eichorn’s office did not respond to a request for comment.

The Senate Republican Caucus called on Mr. Eichorn to step down on Tuesday. “We are shocked by these reports and this alleged conduct demands an immediate resignation,” the caucus said in a statement. “Justin has a difficult road ahead and he needs to focus on his family.”

Mr. Eichorn, who was elected to the State Senate in 2016, represents a largely rural district in northern Minnesota. He is married and has four children, according to his campaign website.

His name has been in the news in recent days because he is one of the sponsors of a state bill that would recognize “Trump Derangement Syndrome” as a form of mental illness.

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.