George Conway, the husband of White House counselor Kellyanne Conway, slammed Donald Trump on Tuesday, saying his “stupidity knows no bounds” after Trump ripped into former aide Cliff Sims for his tell-all book.

Early Tuesday Trump lashed out at his former aide Cliff Sims, tweeting, “A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction. He pretended to be an insider when in fact he was nothing more than a gofer. He signed a non-disclosure agreement. He is a mess!”

A low level staffer that I hardly knew named Cliff Sims wrote yet another boring book based on made up stories and fiction. He pretended to be an insider when in fact he was nothing more than a gofer. He signed a non-disclosure agreement. He is a mess!

— Donald J. Trump (@realDonaldTrump) January 29, 2019

George Conway’s response was perfect:

Your stupidity knows no bounds. https://t.co/Ac6eQmTgOx

— George Conway (@gtconway3d) January 29, 2019

Conway’s criticism attracts increased attention, particularly on social media, due to his wife’s role as a senior adviser and close confidant of Trump’s.

Donald Trump’s son Eric is one of the people who has called out George Conway for his attacks, saying it’s disrespectful to his wife Kellyanne.

Eric Trump once tweeted, “Of all the ugliness in politics, the utter disrespect George Conway shows toward his wife, her career, place of work, and everything she has fought SO hard to achieve, might top them all,” tweeted Trump, whose father has himself been accused of disrespecting women on more than one occasion. Kellyanne Conway is great person and frankly his actions are horrible.”

Of all the ugliness in politics, the utter disrespect George Conway shows toward his wife, her career, place of work, and everything she has fought SO hard to achieve, might top them all. @KellyannePolls is great person and frankly his actions are horrible.

— Eric Trump (@EricTrump) December 4, 2018

George Conway, who initially supported Trump, has become one of the president’s fiercest conservative critics. An attorney, he has called Trump’s appointment of Matthew Whitaker as acting attorney general “unconstitutional,” and, last month, he referred to the administration as a “dumpster fire.”