As markets melted down in March, the Federal Reserve unveiled novel programs meant to keep credit flowing to states, medium-sized businesses and big companies — and Congress handed Treasury Secretary Steven Mnuchin $454 billion to back up the effort.Nine months later, Senate Republicans are trying to make sure that those same programs cannot be restarted after Mr. Mnuchin lets them end on Dec. 31. Beyond preventing their reincarnation under the Biden administration, Republicans are seeking to insert language into a pandemic stimulus package that would limit the Fed’s powers going forward, potentially keeping it from lending to businesses and municipalities in …
