U.S. Sen. Chuck Grassley should have denounced what was essentially a threat of violence issued at a town hall forum, a Washington, D.C.,-based gun-control organization said Tuesday.

The Brady Campaign to Prevent Gun Violence was responding to an exchange Grassley had with a constituent in Pocahontas Monday. The man, who identified himself as Tom Eisenhower, said President Barack Obama is acting like a “little Hitler” and then told the audience “I’d take a gun to Washington if enough of you would go with me.”

“It was a credit to the senator’s audience that they booed Mr. Eisenhower, but Sen. Grassley also has a responsibility as an elected official to categorically denounce Mr. Eisenhower’s statement and the sentiment behind it,” said Doug Pennington, assistant director of communications for Brady Campaign to Prevent Gun Violence.

Grassley may not have taken the threat seriously, Pennington said, since Eisenhower appears to be a senior citizen.

“Yet we recently saw 88 year-old James W. von Brunn shoot and kill a security officer at the Holocaust Memorial Museum here in Washington, DC,” he said.  “Sen. Grassley should have taken Mr. Eisenhower and his words very seriously.”

Pennington said it is a “tense time in America,” pointing to news reports of people with assault weapons at a presidential event in Arizona and another armed protester at a presidential event in New Hampshire.

The Brady Campaign to Prevent Gun Violence is a non-profit organization named after James Brady, press secretary to U.S. President Ronald Reagan who was shot in the head and paralyzed for life following an assassination attempt.