Senate Majority Leader Mitch McConnell said that Corker was "an important part" of the Senate Republican caucus when asked if he agrees with comments from Sen. Bob Corker, R-Tennessee, that the White House is an "adult day care center."

"Senator 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, and he's an important part of our team," McConnell said following an event with EPA Administrator Scott Pruitt Monday morning in Hazard, Kentucky.

A reporter asked McConnell a follow-up question about whether he shares Corker's sentiment.

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"[Corker is] an important part of our team and he's a particularly important part of the budget debate which will be on the floor next week," McConnell said, offering a reminder that Corker is critical to the president's hopes of passing tax legislation this year.

Corker announced in September that he will retire at the end of his term in 2018.

President Trump bashed Corker in a series of tweets Sunday morning, saying the senator "begged" for his endorsement for re-election, which Mr. Trump claims he refused. He also said Corker is "largely responsible for the horrendous Iran Deal" and said he "didn't have the guts to run."

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

Corker fired back shortly after:

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's chief of staff Todd Womack refuted the president's claim that he had refused to endorse Corker. Womack said that in fact, the president asked Corker to reconsider his decision not to run and told the Tennessee senator he'd have his endorsement.

Corker went even further in his comments about Mr. Trump in an interview with the New York Times, in which he remarked that Mr. Trump is running the West Wing "like he's doing 'The Apprentice' or something." He said the president is concerning him and his threats toward other countries could set the U.S. on a "path to World War III."