WASHINGTON (MarketWatch) - The Federal Reserve on Wednesday left a key U.S. interest rate unchanged, but the central bank also took note of rising prices and said it now expects inflation to "run near" its 2% target "over the medium term." The somewhat more hawkish language about price levels suggests the Fed is more worried about inflation, but not unduly alarmed. Still, the changes in the central bank's policy statement could boost expectations that the Fed will raise its benchmark rate four times in 2018 instead of three as previously planned. The short-term fed funds rate was raised in March to a range of 1.5% to 1.75%. The vote to hold rates steady in May was 8-0.