Kinzinger called the former president a “snowflake” and “one of the weakest men that I’ve ever seen” in an interview Monday with CNN’s Anderson Cooper.

The comment came amid a discussion about Trump’s vitriolic response to predecessor George W. Bush’s speech on the 20th anniversary of the Sept. 11 terrorist attacks.

Bush on Saturday said there is “little cultural overlap between violent extremists abroad and violent extremists at home.” Trump hit back Monday, saying Bush “shouldn’t be lecturing anybody” because of his role in “getting us into the quicksand of the Middle East.”

Kinzinger, a frequent critic of the twice-impeached Trump, suggested the response demonstrated a lack of strength.

“I mean, If you think about it, what is strength? Strength isn’t somebody that just gets their dander up every time because they feel they have such a lack of self-esteem, they feel they have to out an attack,” said Kinzinger. 

“Somebody with strength is someone who can take criticism, who can go out on a day like Sept. 11 and bring people together,” he continued. “Folks on my side like to use the term snowflake when talking about people that get offended really easy. Well, that’s Donald Trump.”

“I look at who he is as a person and the amount of offended he gets on anything and how he has to go out and punch down,” Kinzinger added. “He’ll attack a radio host, for goodness sakes, when he was president of the United States.”

See Kinzinger’s full interview on CNN here: