“My forecast does not see inflation rising to our 2 percent target until 2018 -- for me, that’s too far down the road given how long we have underrun our target,” Evans said in remarks prepared for a speech Monday in Stockholm. “The way to avoid a loss of credibility about our symmetric target is to make sure we have enough accommodation in place to achieve our 2 percent objective in a timely manner.”

The Fed has said it will raise its benchmark federal funds rate -- which has been near zero since December 2008 -- when it sees further labor-market improvement and is “reasonably confident” inflation will rise back to its 2 percent goal over time. Most economists in a Bloomberg survey late last month predicted the central bank will start tightening in September.

Evans, a voting member of the policy-setting Federal Open Market Committee this year, said officials will decide on a meeting-by-meeting basis. He said while it’s possible a case for tightening could be made in June, depending on the data, his outlook means he’s in favor of the current level of stimulus continuing.

“If the data from the committee standpoint indicates that it’s sufficient to have confidence in inflation going to move up and if we have confidence about the path of the economy we see through first-quarter softness, you could imagine a case being made for a rate increase in June,” he said. “My own projection is that it will take quite some time” for inflation to meet the target.

Fed Indicator

The Fed’s preferred gauge of price pressures, based on personal consumption expenditures, rose by 0.3 percent in March from a year ago and has been under policy makers’ official target for 35 consecutive months.

“My current view is that my economic outlook and my assessment of the balance of risks will evolve in such a way that I likely will not feel confident enough to begin to raise rates until early next year,” Evans said.

To make sure the economy has enough momentum to decisively lift inflation, Evans argued the U.S. central bank should make sure its policy is loose enough to allow the possibility that the rate of price increases will overshoot the Fed’s target. This would help persuade the public that the Fed really is aiming for 2 percent.

“Symmetry is crucial,” he said. “We need the probability that inflation is above 2 percent to be the same as the probability it will be below 2 percent.”