A U.S. congressman from Minnesota said that anonymous threats have been coming to his office from opponents of gun control, reported Think Progress.

On MSNBC's UP with Chris Hayes on Saturday, Rep. Rick Nolan (D) told the host, "We've been getting a lot of not very thinly-veiled threats and calls into my office. You know, things like, 'You tell him he better watch his back.' Nobody has actually come out and said they’re gunning for me, but the messages are quite angry, vitriolic, and a little bit frightening to people at my front desk who have been taking the calls. I’m a little nervous about it. I’ve never been nervous before."

He went on to say that the NRA is "very toxic in the effect they’re having on the American public."

He also said that the NRA's Wayne LaPierre was traveling with his opponent, "going from town to town" and called "anybody in my district that had ever gotten a hunting license" to tell them that Nolan wanted to take their guns.

Nolan protested that he is a "big Second Amendment supporter."

"I think there's been a big change in the national sentiment. Those who are timid about maybe supporting gun control but were afraid politically, they need to get over it. I think people want some controls," he said.

Other recent threats in response to the debate on gun control have not gone unnoticed by authorities. Glenn Allen Kirkham was arrested and is facing an FBI charge after allegedly making threats online, reported the Associated Press Jan. 15.

Watch the video below.