The Federal Reserve is between a rock and a hard place right now, according to one expert.
Ethan Harris, Bank of America's co-head of global economics research, told CNBC's "Squawk on the Street" on Wednesday that the central bank raising interest rates is a "tough call" for a number of factors. "The unemployment rate alone would be enough to trigger the Fed by this summer," he said. "Meanwhile, though, inflation in the U.S. is dropping; not just headline inflation, but the [core inflation]."
"The Fed [will be] achieving one of its goals with the low unemployment rate, but they'll be missing the other one," Harris added. "That's what makes it so uncertain."
The central bank will release a statement following its meeting at 2 p.m. ET.
Harris said the drop in oil prices and the dollar's rise also breed uncertainty as to how the Fed will act. "The main news from the lower oil is going to be stronger growth because it helps the U.S. consumer and the lower inflation due to the price effects," he said. "That makes the Fed's decision very complicated [because] it pulls them into two different directions."
Nevertheless, Harris said he believes the Fed will raise interest rates later this year. "We have them going in September, although I think almost anytime during the second half is a reasonable guess."