(CNN) The chairman of the Senate Veterans' Affairs Committee refused Monday to agree with President Donald Trump's criticism of the panel's top Democrat, Sen. Jon Tester of Montana, nor the President's call for the Montana Democrat to resign in the wake of the Dr. Ronny Jackson scandal.

"I'm not in the critiquing business," Sen. Johnny Isakson, a Georgia Republican, told reporters in the Capitol after overseeing a short pro-forma session of the Senate, which is otherwise recessed.

In fact, Isakson defended Tester's decision to publicly release the allegations against Jackson, saying that "every senator has the right to exercise their options" and "that's the way it should be."

Isakson said that since Jackson had withdrawn his nomination to be veterans affairs secretary, the committee is no longer investigating allegations about the White House doctor and problems at the White House Medical Office. Asked if he thought they were true, Isakson pointed to a letter he and Tester sent to the White House last week seeking information about the charges and noted that the White House never responded to it.

"We never got that response back, and that's why we didn't have the hearing," Isakson said.

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