The sluggish U.S. economy shows signs of gaining strength but still needs a lot of help from the Federal Reserve to get back on track, a top Fed policy maker said on Friday.

Chicago Federal Reserve Bank President Charles Evans said the Fed’s controversial $600 billion bond-buying program is necessary both because unemployment is too high and inflation is too low.

“More recent data have been coming in somewhat stronger. But they do not yet point to the kind of robust, self-perpetuating recovery that we need in order to close today’s large resource gaps within a reasonable amount of time,” Evans said in remarks prepared for delivery to an economics conference.

Evans, a voter this year on the Fed’s policy-setting panel, said the economy’s current status warrants an easy monetary policy.

“Even if the Fed were charged with achieving price stability alone, as are many other central banks, undershooting our inflation target would dictate a highly accommodative monetary policy stance,” Evans said.