Trump was widely criticized for his meandering answer to the softball question, in which he promoted his experience and attacked former national security adviser John Bolton instead of focusing on initiatives and policies he’d promote if given another four years in office.

“You make some mistakes. Like, you know, an idiot like Bolton,” Trump said during the interview. “All he wanted to do was drop bombs on everybody. You don’t have to drop bombs on everybody. You don’t have to kill people.”

And on Saturday morning, Trump tweeted a defense of his Fox News interview, saying Hannity “dominated T.V. with my interview on Thursday night.”

Grassley, calling it the most important question of the interview, said Trump should have communicated to voters his desire for continuing to “DRAIN THE SWAMP” and appoint more conservative justices to the Supreme Court.

The criticism from Grassley comes a day after he encouraged Trump to heed the advice of a scathing Wall Street Journal editorial that warned Trump could only serve one term.

“Will somebody w access to the Oval Office read the WSJ editorial ‘The Trump Referendum’ to President Trump,” Grassley wrote in a tweet on Friday. “We won’t hv more good scotus justices or the best economy in 50 years like we hv had if he doesn’t follow that advice.”