Mr. Long, a former Republican congressman and staunch ally of Mr. Trump, is expected to be nominated to an ambassadorship instead, the people said. It is unclear who will next lead the I.R.S., which has had six different people in charge this year. Treasury Secretary Scott Bessent will serve as acting commissioner until a permanent replacement takes office, a senior administration official said.

Like a monkey with a gun.

Trump Is Removing I.R.S. Chief 2 Months After He Was Confirmed