The Federal Reserve should continue gradually raising U.S. interest rates given low inflation should rebound, an influential Fed policymaker said in a Thursday speech that sounded slightly less confident than his previous hawkish comments in the face of weak price readings.

New York Fed President William Dudley did not repeat an assertion three weeks ago that he expects to raise rates once more this year, and he called the persistent shortfall in prices surprising. Yet he reinforced the U.S. central bank’s general expectation that an inflation rebound is around the corner, allowing it to continue tightening monetary policy before too long.

The comments reflect intellectual divisions within the Fed and could whip-saw investor expectations since they come two days after a Fed governor, Lael Brainard, expressed deeper concern over the inflation data.

“Even though inflation is currently somewhat below our longer-run objective, I judge that it is still appropriate to continue to remove monetary policy accommodation gradually,” said Dudley, a permanent voter on policy and a close ally of Fed Chair Janet Yellen.

The central bank has raised rates twice this year in a nod to decent economic growth, falling unemployment and solid job gains. Yet months of falling or flat inflation readings have flummoxed policymakers and caused investors to grow skeptical of a December rate hike, as implied in Fed forecasts from June.

Dudley, who also predicted the Fed’s bond portfolio would shrink to $2.4 trillion to $3.5 trillion by early next decade, said the inflation weakness may hint at “structural factors” that would be positive for the economy and for workers.

The Fed’s preferred inflation measure is now 1.4 percent. But Dudley said the falling dollar and “the fading of effects from a number of temporary, idiosyncratic factors” means that inflation will rise to the Fed’s 2-percent goal “over the medium term.”

“I expect that the U.S. economy will continue to perform quite well,” he added.

Dudley swatted away criticisms from doves in arguing it may be necessary to tighten with inflation below target, since monetary policy acts with a lag. He also largely dismissed worries over possible asset bubbles and criticisms that the Fed has contributed to price distortions and low market volatility.

Dudley said he hoped that the inflation puzzle would be clearer in “coming months.” And he nodded to another favorite reason to expect to keep raising rates: financial conditions — from credit spreads to stocks to bond yields — remain quite loose despite past rate hikes.

Traders currently give about a 23 percent probability to a December rate hike, down from 30 percent before Brainard spoke on Tuesday, reflecting the weak inflation readings and some more dovish comments from Fed policymakers. The central bank’s forecasts imply roughly three rate hikes next year.

It is widely expected, however, that the Fed will announce at a Sept. 19-20 policy meeting the beginning of trimming its $4.5-trillion bond portfolio, likely starting in October.

Dudley, whose New York Fed manages the portfolio, said he expects the process to start this year. He added that the shedding of Treasury and mortgage bonds would exert only a “modest” policy tightening over the years.

Nodding to the effects in Texas of Hurricane Harvey, Dudley said that while the human toll was tragic, and there may be some gasoline-price inflation, they should not fundamentally alter the overall economy’s momentum