"President Trump's unprecedented removal of Inspector General Linick is only his latest sacking of an inspector general, our government's key independent watchdogs, from a federal agency," Engel and Menendez wrote in a letter to the White House. "We unalterably oppose the politically-motivated firing of inspectors general and the President's gutting of these critical positions."
The announcement of the investigation was also tweeted by Menendez Saturday afternoon.
A senior department official said Trump removed Steve Linick from his job on Friday but gave no reason for his ouster.
In a letter to Congress, Trump said Linick, who had held the job since 2013, no longer had his full confidence and that his removal would take effect in 30 days.
Trump did not mention Linick by name in his letter.
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