Federal Reserve Bank of San Francisco president John Williams, who will vote on policy this year, said raising US interest rates in June would be a close call amid "strong momentum" in the labour market and weaker wage gains.
"I would expect by June that the argument pro and con for lifting off rates will be probably a close call" assuming that inflation doesn't fall further, Williams said. "It's a reasonable guess."
His remarks dovetailed with earlier comments from Atlanta Fed chief Dennis Lockhart, also a voting member of the policy-setting Federal Open Market Committee this year, that rate liftoff in mid-2015 would probably be justified.
US stocks extended declines on the comments by Williams before markets closed in New York. The Standard & Poor's 500 Index ended 0.8 per cent lower at 2028.26.
Fed chairwoman Janet Yellen said last month not to expect the central bank to raise rates before the end of April, leaving expectations intact for a move around mid-year following sustained labour market improvements.