President Donald Trump falsely claimed at a Kansas rally Monday that GOP Sen. Roger Marshall, who is a doctor, was required by law to sue his patients for unpaid medical bills and got a “bum rap.”

Marshall’s reelection bid took a hit when The New York Times reported that he had sued more than 700 patients when he worked as an OB-GYN, and dozens were arrested for missing court dates. Experts said such aggressive bill-collecting is rare.

Marshall is now locked in a tight race against Democrat Adam Hamilton, who leads in many polls.

“He was given a bum rap, because he was mandated by law to request — strongly — money owed from patients,” Trump said of Marshall. “You’re not allowed not to do it. You have to, by law, go after those people. And they made it like, ‘Oh, he was some kind of a Shylock type guy.’ ”

“And if he didn’t make these requests, he would be breaking the law,” the president continued. “He would have been breaking a very strong criminal law, and he would be subject to criminal arrest and liability.”

The Kansas City Star pushed back at the claim, writing, “No federal or state law requires doctors to sue patients over unpaid medical debt.” The newspaper also referenced a previous report from The Hill that disputed a similar claim made by Trump on the matter. “There is no law requiring debt collectors to ask judges for arrest warrants for defendants who fail to appear in court,” the news outlet wrote.

“That man did nothing wrong,” Trump insisted on Monday.

The president tainted his assertion further by using “Shylock,” the Jewish lender and villain in “The Merchant of Venice” whose name is now considered an antisemitic slur. And it wasn’t the first time Trump has done so.