Washington, DC CNN  — 

Republican Sen. Mitt Romney on Saturday denounced President Donald Trump’s firings of internal government oversight officials, calling it a “threat to accountable democracy.”

Romney’s comments came in response to Trump’s Friday firing of State Department Inspector General Steve Linickthe latest in a series of dismissals of independent government watchdogs that have come in the wake of the President’s acquittal on two articles of impeachment earlier this year.

“The firings of multiple Inspectors General is unprecedented; doing so without good cause chills the independence essential to their purpose. It is a threat to accountable democracy and a fissure in the constitutional balance of power,” the Utah Republican tweeted.

Romney is the only Senate Republican who voted to convict Trump of abuse of power earlier this year.

Linick’s dismissal drew immediate condemnation from top Democrats who accused the President of engaging in a pattern of retaliation against public servants charged with oversight of his administration. Sen. Bob Menendez, the top Democrat on the Foreign Relations Committee, called it “another Friday night massacre” on CNN Saturday night after announcing earlier in the day that he and his House counterpart, Foreign Affairs Chairman Eliot Engel, had launched a probe into the firing.

The letter that announced Linick’s firing, first reported by Politico, stated that the dismissal will take effect in 30 days unless members of Congress intervene to pressure or convince the President to reverse course.

Though Republicans have been mostly quiet about the firing, earlier in the day, Republican Sen. Chuck Grassley, a longtime proponent of inspectors general, expressed some concern about Trump’s rationale for firing Linick.

“As I’ve said before, Congress requires written reasons justifying an IG’s removal. A general lack of confidence simply is not sufficient detail to satisfy Congress,” Grassley said in a statement.

Late Saturday night, Maine Sen. Susan Collins also responded to the firing in a series of tweets that suggested Linick’s dismissal didn’t meet the standard required by law.

“The President has not provided the kind of justification for the removal of IG Linick required by this law,” said Maine Sen. Susan Collins, referencing a law she co-authored in 2008, as part of a Twitter thread.

This story has been updated with additional developments.

CNN’s Jeremy Diamond, Zachary Cohen and Manu Raju contributed to this story.