The Federal Reserve may already have the so-called shadow chairman that President Donald Trump has said he might soon appoint in a move that could be seen as part of a pressure campaign to lower interest rates and reduce government borrowing costs.

Top voices on Wall Street have expressed alarm over the idea that Trump could fire Fed Chair Jerome Powell, emphasizing the need for Fed independence.

President Donald Trump sent the U.S. stock market on a jagged round trip after saying he had “talked about the concept of firing” the head of the Federal Reserve.