President Donald Trump has opened up a new front in his attack on the Federal Reserve and its chair, Jerome Powell: He says the alledged mismanagement of a building renovation project could be grounds for firing Powell.

The independence of central banks, which allows policymakers to operate free from political meddling, is considered sacrosanct by investors and economists.

President Donald Trump’s attacks on Federal Reserve Chair Jerome Powell are so commonplace at this point that they barely register in financial markets these days. The rapidly intensifying multi-pronged efforts by Trump’s advisers to amplify and expand on Trump’s attacks are a good reason to rethink that indifference.