The Federal Reserve could well raise interest rates as soon as June, two top U.S. central bankers said on Friday, so long as economic data strengthens as expected from a dismal first quarter. That view—from the hawkish-leaning chief of the Cleveland Fed and from the centrist head of the San Francisco Fed—is at odds with the view of many traders, whose bets in the interest-rate futures markets suggest they have all but discounted a June rate hike and now expect the Fed to wait until December before raising rates for the first time since 2006. The Fed has kept interest...