Once again, the Federal Reserve has regrettably become a favorite whipping boy.

President Trump has been lobbying it to lower interest rates, even though the unemployment rate is 3.8 percent. Progressives are still complaining that the central bank didn’t do enough to stimulate the economy in the wake of the 2008 recession.

More worrisome, Mr. Trump has been attacking the Fed’s actions with more vitriol than any previous president in memory while proposing two highly partisan and unqualified nominees to join a distinguished board that has historically been free of any political agenda.

The policy critics on both sides are about as wrong as imaginable. And above all, we need to guard the independence of the central bank, the most important government institution that has not been divided by the deep partisanship so evident elsewhere.

In an era when even the Supreme Court divides routinely along ideological lines, the Fed still maintains an analytical and, as the former chairman Janet Yellen liked to say, data dependent approach to policymaking.