Lisa Cook, a governor of the U.S. Federal Reserve, has filed a lawsuit against former President Donald Trump, challenging his attempt to remove her from office. In her legal petition, Cook has requested the court to declare Trump’s dismissal order “illegal and null.”

The lawsuit also names Federal Reserve Chairman Jerome Powell as a co-defendant. Trump has accused Cook of providing false information regarding her mortgage records and claims that the Constitution gives him the authority to remove her from her position.

Cook has previously stated that there is no “legitimate legal basis” for her dismissal under U.S. law. According to reports from the BBC, the move by Trump comes amid his dissatisfaction with the Federal Reserve’s reluctance to lower interest rates. As a member of the board responsible for setting U.S. interest rates, Cook’s role places her at the center of this high-stakes confrontation.