FILE PHOTO: U.S. President Donald Trump looks on as Jerome Powell, his nominee to become chairman of the U.S. Federal Reserve, speaks at the White House in Washington, U.S., November 2, 2017. REUTERS/Carlos Barria/File Photo

WASHINGTON (Reuters) - U.S. President Donald Trump on Tuesday further sought to pressure the Federal Reserve as the central bank prepared to start its two-day policy meeting, warning the Fed’s board not to “make yet another mistake” ahead of an expected interest rate hike.

The Federal Open Market Committee is expected to raise interest rates for the fourth time this year during its two-day meeting on interest rate policy that is due to start later on Tuesday.

The Fed, which has been raising interest rates in 25-basis-point increments since December 2015, has promised to raise rates gradually toward a neutral setting to keep the economy from overheating. Many economists also expect additional increases next year although at a slower pace.

Trump, who has made the economy a key part of his political platform, has repeatedly criticized the Fed and its chairman, Jerome Powell.

“Don’t let the market become any more illiquid than it already is. Stop with the 50 B’s. Feel the market, don’t just go by meaningless numbers. Good luck!” Trump wrote.