Donald Trump is studying whether he’s able to fire Federal Reserve Chairman Jerome Powell, his top economist said Friday, a day after the president publicly criticized the head of the central bank for not moving fast enough to slash interest rates.

President Donald Trump on Thursday ratcheted up his criticism against Federal Reserve Chair Jerome Powell, calling for his “termination” for not cutting interest rates quickly enough. His comments come one day after the central bank chief delivered a stark warning about the effect of Trump’s sweeping tariffs on the economy.