Jerome Powell remained confident in the Federal Reserve's independence as it faces legal battles against US President Donald Trump's administration, which include an investigation into the Fed chair.
"I'm strongly committed to that, and so are my colleagues," he told reporters on Wednesday after the Fed held interest rates steady at about 3.64 per cent.
Among the other legal battles the Fed faces is Mr Trump's attempted removal of Fed governor Lisa Cook.
During arguments before the Supreme Court last week, the nation's top judges appeared deeply reluctant to allow Mr Trump to remove Ms Cook from the Fed's board of governors. The case is regarded as a broader test of the US central bank's independence, which has been under immense pressure from the Trump administration to lower interest rates.
Mr Powell attended the argument last week in a sign of support for the embattled Fed official.
"I will tell you why I attended," he said during a news conference on Wednesday. "That case is perhaps the most important legal case in the Fed's 113-year history and … it might be hard to explain why I didn't attend."
No Fed official in the central bank's history has ever been fired, and analysts believe that a ruling in favour of Mr Trump could open the door for other Fed officials to be fired in the future. Conservative Justice Brett Kavanaugh, considered a swing vote on the bench, argued that doing so could "would weaken, if not shatter, the independence of the Federal Reserve".
Mr Trump tried to fire Ms Cook last August over mortgage fraud allegations, claims she denies and argues is an effort to install another member on the Fed board who would be more inclined to deliver steep rate cuts.
The move was an unprecedented step in his effort to exert more control over the Fed. Presidents can only fire Fed officials "for cause", which is thought to mean malfeasance or neglect of duty.
In an even more extraordinary escalation between the White House and the Fed, Mr Powell revealed this month that he was under criminal investigation by the Justice Department over remarks he made before the US Senate last year concerning the central bank's renovation project. He has called the investigation a "pretext" to pressure the central bank to lower interest rates.
Mr Powell refused to answer questions on the investigation, and did not respond when asked if the Fed responded to grand jury subpoenas it received this month.
"I think the fact that he combines both the charge against Lisa Cook and the charge against himself as being politically motivated to get interest rates lower, kind of spoke for itself," said Art Hogan, chief market strategist at B Riley Wealth.
The Fed fiercely guards its independence in setting the nation's interest rates, which economists consider an essential ingredient to maintaining economic stability. Mr Powell said it would be difficult to retain that independence if lost.
"It's just an institutional arrangement that has served the people well, and that is ... to not have direct elected official control over the setting of monetary policy," he said.
Mr Powell's term as Fed chair expires in May, and Mr Trump is expected to announce his nominee to replace him imminently. Mr Powell is still able to serve on the Fed board for another two years as a Fed governor, although he offered no clues on his future.
"There's a time and place but not something I'm going to get into today," he said.
