The central bank is poised to hold interest rates steady this month, but there could be a path to cut as early as September.

If investors start to worry the Fed is no longer independent, fewer may buy U.S. bonds, which would push up the interest rate on those bonds and lift borrowing costs more broadly.

The president prefers low interest rates. But the Federal Reserve Act protects the Fed chair's removal. Long-term rates are set by financial markets and sensitive to inflation expectations.