After Attorney General Jeff Sessions on Wednesday sent a letter to Senate Judiciary Chair Chuck Grassley (R-IA) criticizing the senator’s criminal justice legislation, Grassley tore into the attorney general in a tweet and several interviews.

Incensed by Sessions letter An attempt to undermine Grassley/Durbin/Lee BIPARTISAN criminal justice reforms This bill deserves thoughtful consideration b4 my cmte. AGs execute laws CONGRESS WRITES THEM! — ChuckGrassley (@ChuckGrassley) February 14, 2018

Grassley followed up in interviews with Politico and Bloomberg News explaining his ire toward Sessions. Grassley told Bloomberg News that he was especially angry with Sessions’ letter considering how much support he gave Sessions through his nomination process and the Russia investigation.

“I think it’s legitimate to be incensed and I resent it, because of what I’ve done for him. He had a tough nomination, a tough hearing in my committee,” Grassley told Bloomberg News.

“They wanted to call him back every other day for additional hearings about his Russian connection, and I shut them off of that until we had the normal oversight hearing in October I believe it was, see? And the President was going to fire him, and I backed him, you know? So why wouldn’t I be irritated?” he added.

In his letter to Grassley, Sessions claimed that the criminal justice bill Grassley worked on with Sen. Dick Durbin (D-IL) would “reduce sentences for a highly dangerous cohort of criminals.” The bill is expected to pass the Judiciary Committee Thursday, but faces tough odds after that.

The bill would give judges more room to reduce prison sentences for nonviolent drug crimes, but the legislation also bolsters punishment for other crimes, such as for those involved in crimes related to the trafficking of opioids.

Grassley complained that Sessions was acting like a senator, not an attorney general by sending the letter.

“It’s Senator Sessions talking, not a person whose job it is to execute law, and quite frankly I’m very incensed,” he told Politico.

Grassley told Politico that if Sessions wanted to undermine the legislation, he “should have done what people suggested to him before: resign from attorney general and run for the Senate in Alabama again.”

He told Bloomberg News that he pitched his bill to the White House, with limited success, but that he feels unsupported by Sessions and President Donald Trump.

“I’ve got people in the White House sympathetic to it but feel corralled by Sessions and a president that hasn’t dug into it,” Grassley said.