Rene A. Boucher of Bowling Green, Ky., is expected to plead guilty in federal court, where prosecutors will seek a sentence of up to 21 months, his lawyer said.
One of the Kentucky senator’s neighbors tackled him in his yard, according to a criminal complaint. It is unclear when Mr. Paul will return to work.
The senator suffered a minor injury in the attack, which happened on Friday afternoon, officials said. A man described as an acquaintance of Mr. Paul’s was charged.
DeAndre Harris, 20, sustained wrist and head injuries when he was beaten by men inside a parking garage in August. He is now accused in the same case.
The authorities announced that they had charged 12 Turkish security personnel and four other American and Canadian civilians in connection with an attack on protesters.
The sentence for Mr. Gianforte, the Montana representative-elect, includes a fine and anger management classes, but no jail time.