Sen. Charles E. Grassley told both retiring Sen. Bob Corker and President Donald Trump to ease up on their feud.

Grassley said he didn’t see how the conflict between the two Republicans was productive, “And I think it would help if the president would be the first to cool it,” the Iowa Republican told The Associated Press, which attempted to contact all 52 Republican senators for their take on the war of words.

“I think it would be better if we stuck to the issues and leave personalities out of it,” Grassley said.

Trump, ratcheted up the feud more on Tuesday, apparently mocking the senator’s height by referring to him as “Liddle’ Bob Corker,” and saying he was “set up” by the “Failing @nytimes.”

The Failing @nytimes set Liddle’ Bob Corker up by recording his conversation. Was made to sound a fool, and that’s what I am dealing with!

— Donald J. Trump (@realDonaldTrump) October 10, 2017

Other GOP senators demurred when asked about Corker’s comments, the AP reported. Senate Majority Leader Mitch McConnell gave a dismissive statement when asked about it in his home state of Kentucky.

“Sen. Corker is a valuable member of the Senate Republican caucus and he’s also on the Budget Committee and a particularly important player as we move to the floor on the budget next week,” McConnell said.

Grassley’s admonition comes after Trump tweeted on Sunday that Corker “begged” the president to endorse him for re-election but that he declined, and that led to Corker announcing he would retire.

Senator Bob Corker “begged” me to endorse him for re-election in Tennessee. I said “NO” and he dropped out (said he could not win without…

— Donald J. Trump (@realDonaldTrump) October 8, 2017

..my endorsement). He also wanted to be Secretary of State, I said “NO THANKS.” He is also largely responsible for the horrendous Iran Deal!

— Donald J. Trump (@realDonaldTrump) October 8, 2017

…Hence, I would fully expect Corker to be a negative voice and stand in the way of our great agenda. Didn’t have the guts to run!

— Donald J. Trump (@realDonaldTrump) October 8, 2017

In response, Corker tweeted that it was “a shame” that the White House had devolved into “an adult day care center,” and said “somebody obviously missed their shift this morning.”

It’s a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.

— Senator Bob Corker (@SenBobCorker) October 8, 2017

Corker, who is chairman of the Senate Foreign Relations Committee, continued his invective against the president in a New York Times interview saying that Trump’s recklessness could set the U.S. “on the path to World War III.”