Washington(CNN) The longest-serving Republican senator in history offered a sharp rebuke Thursday to anyone recommending that President Donald Trump fire special counsel Robert Mueller.

"Anyone advising the President — in public or over the airwaves — to fire Bob Mueller does not have the President or the nation's best interest at heart. Full stop," Sen. Orrin Hatch, R-Utah, tweeted.

The Utah Republican's remarks comes shortly after Trump's tweet early Thursday morning that if he wanted to fire Mueller, "I would have fired him" after it was reported he has discussed firing Mueller for months.

Trump has increased his attacks against Mueller after FBI agents raided his attorney Michael Cohen's office and hotel room Monday. The President lashed out at Mueller's investigation, calling it a "disgrace" and publicly mulling if he should get rid of Mueller.

White House press secretary Sarah Sanders told reporters on Tuesday that the President "certainly believes he has the power" to fire Mueller.

Back in March -- when Trump first attacked Mueller by name on Twitter -- Hatch said in a statement that he has urged the White House "in public and in private to allow the special prosecutor to continue his investigation uninterrupted."

"I know Bob Mueller well and believe him to be a straight shooter, and I continue to believe that giving him the time and support necessary to get to the bottom of things is in the best interest of all parties involved," Hatch said.

Hatch joins other top Senate Republicans who have also argued it would be ill advised and cataclysmic for Trump's presidency to fire Mueller, but believe that legislation to protect Mueller is unnecessary.

"I do not believe the President would take such a foolish action," Hatch said in his statement in March.