WASHINGTON, May 31 (Reuters) - U.S. Federal Reserve Governor Jerome Powell on Sunday warned about the impact of a politicized Fed and made a broader call for the defense of democratic institutions in his first public remarks since the end of his eight-year stint as head of the central bank. 

"Democratic institutions take much time, effort, and patience to build but can be torn down all too quickly," Powell said in remarks prepared for delivery as he accepted the John F. Kennedy Profile in Courage Award, given by the John F. Kennedy Library Foundation.

"It is essential that we preserve what is good about these institutions, even as we strive to improve them," said Powell, who included the Fed along with the courts and universities as among the core institutions key to the country's success and standing in the world. 

"Like many other institutions, the Fed has been undergoing a stress test," Powell said, which in the central bank's case has included efforts by President Donald Trump to fire Fed Governor Lisa Cook, calls for Powell's resignation, and a criminal probe of Powell. 

MINNEAPOLIS/ST. PAUL CITIZENS ALSO HONORED

Powell's term as chair formally ended on May 15. His successor, Kevin Warsh, was sworn in as Fed chair on May 22. Powell has decided to continue as a Fed governor in part because of what he regards as ongoing threats to the Fed's independence, a decision that effectively prevents Trump from appointing another member to the Fed board for now.

The Fed's structure is meant to allow it to make monetary policy decisions free of political considerations, and "these protections have served the public well, and administrations from both parties have respected them," Powell said. "If any administration finds a way to remove Fed officials over policy differences, then future administrations will do so as well. The public would lose faith that the central bank will make decisions based only on what's best for all Americans." 

In announcing the award to Powell earlier this year, the foundation said he had "safeguarded one of the country's most essential apolitical institutions and demonstrated extraordinary courage in the face of sustained personal and professional risk."

The award this year was also given to the citizens of Minneapolis and St. Paul for the public response to the surge in immigration enforcement in the Twin Cities area,  including protests and efforts to monitor government enforcement efforts.