Vermont Sen. Bernie Sanders on Sunday called it "distressing" to learn that the man who shot House Majority Whip Steve Scalise and other Republicans last week was a volunteer on his Democratic campaign for president.

"There should not be any violence associated with politics in America," Sanders said during an appearance on CNN's "State of the Union."

The Democratic socialist said he spoke to more than 1.4 million people during his presidential rallies and is convinced his supporters believe "violence is not acceptable."

"So, obviously it was distressing to find out that this particular person had been a volunteer, I believe, in Iowa for a period of time," Sanders said.

Asked by host Jake Tapper, the senator said law enforcement has not been in touch with him about the shooter. "I just want to wish Rep. Scalise a very, very quick recovery," Sanders said. "What happened was a tragedy, unacceptable."

James Hodgkinson of Belleville, Ill. wounded Scalise, a lobbyist, a congressional staffer and two Capitol Police officers when he opened fire during a congressional baseball practice outside Washington last week. Hodgkinson, who was killed by police, lambasted Trump and Republicans while expressing support for Sanders on social media.