They added that in an effort to "confirm that there are clear, substantial reasons" for Atkinson's removal, they are asking Trump to provide a "more detailed reasoning" for his firing by April 13.

The president sent shockwaves through Washington on Friday night when he notified Congress, in the middle of a pandemic, that he was removing Atkinson, who handled the whistleblower complaint relating to Trump's actions toward Ukraine that sparked the House impeachment inquiry.

"It is vital that I have the fullest confidence in the appointees serving as Inspectors General," Trump wrote in the Friday letter. "That is no longer the case with regard to this Inspector General."