Embattled Federal Reserve Chairman Jerome Powell will attend a Supreme Court session Wednesday in the case of the attempted firing of Fed governor Lisa Cook.

Court observers and others say Powell attending the session is an unusual show of support for Cook.

The high court will hear oral arguments on whether President Donald Trump can fire Cook, as he said he would do in late August, according to the Associated Press. 

A person familiar with the matter told the wire service that Powell plans to attend the hearing.

Trump has hinted at firing Powell because the Federal Reserve will not lower interest rates, though recently said it's "highly unlikely" that he will. Also in recent days, the Justice Department has opened a probe into whether Powell misled Congress about the scope and cost of renovating the Federal Reserve headquarters. 

Powell quickly fought back with a video statement in which he suggested the "threat of criminal charges" is retribution for him not lowering rates.