Fed Governor Christopher Waller, at a New York event, said the US central bank should lower borrowing costs at its July 29-30 policy meeting to preserve the labor market’s stren

Christopher Waller, a potential contender to be the next chair of the central bank, said the Federal Reserve should not wait for the labor market to weaken to reduce interest rates.

While almost no one thinks Donald Trump's verbal attacks on Federal Reserve Chair Jerome Powell are a positive development, they have electrified the debate about whether the U.S. president is right that interest rates are too high.

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.

Investors, not the Fed, control the interest rates that matter most to businesses and consumers. They might demand higher returns if the central bank’s independence comes into question.