Mohamed El-Erian, the former CEO of Pimco CEO, tweeted on Tuesday, becoming one of the first mainstream market commentators to do so. The comments from El-Erian, now the president of Queens’ College at Cambridge University, come as anxiety is building among market participants over the Trump administration’s escalating attacks on the Fed. The criticisms have spread to areas beyond the Fed’s rate-setting decisions, threatening to destabilize an institution at the center of economic policymaking. “If Chair Powell’s objective is to safeguard the Fed’s operational autonomy (which I deem vital), then he should resign,” El-Erian posted.