* reuters://realtime/verb=Open/url=cpurl://apps.cp./Apps/econ-polls?RIC=USGDPQP economic poll data
* reuters://realtime/verb=Open/url=cpurl://apps.cp./Apps/cb-polls?RIC=USFOMC%3DECI Fed poll data
BENGALURU, Oct 23 (Reuters) - The U.S. Federal Reserve will raise interest rates in December and twice next year, according to a Reuters poll of economists, who now worry that the central bank will slow its tightening because of expectations that inflation will remain low.
Most respondents expected the nation's economy to determine future rate hikes, but a change in regime at the Fed could also affect monetary policy.
U.S. President Donald Trump could decide this week whether to reappoint Fed Chair Janet Yellen, whose term ends in February, since he has concluded interviews with five candidates for that post.
"There is a greater-than-usual degree of uncertainty around monetary policy next year, with the Fed's leadership up in the air," wrote RBC economist Josh Nye.
A Reuters poll of economists published last week showed Fed Board Governor Jerome Powell getting the top job, although most said reappointing Yellen would be the best option.
Still, a vast majority of the more than 100 economists in the latest poll expect rate hikes to depend largely on how the U.S. economy performs.
"Despite intense speculation about the next Fed chair, the path of policy rates is still likely to be driven primarily by the data, regardless of who is nominated," said Christian Keller, head of economics research at Barclays.
Forty of the 50 economists who answered an extra question also said the U.S. economy, which is on a steady growth path, did not need a big fiscal stimulus in the form of sweeping tax cuts.
The dollar rose on Friday after the Senate approved a budget proposal for the 2018 fiscal year that cleared a critical hurdle for a tax-cut package.
But the need for such a large stimulus to boost the U.S. economy at this late stage of its cycle, when the jobless rate is at more than a 16-year low, remains questionable.
"The U.S. needs to return to a sustainable fiscal path, and I have little faith that sweeping tax cuts will generate enough growth to put us on that path," said Bank of the West economist Scott Anderson.
While recent U.S. economic data has improved, the closely watched core PCE inflation measure has been below its medium-term target of 2 percent for more than five years, despite strong employment growth.
The latest poll, taken Oct. 16-23, showed scant expectations of economic growth lifting off from its current trend or of inflation reaching the Fed's target before 2019.
That has divided Fed policymakers and raised doubts about the pace of further rate hikes, according to minutes from the Sept. 19-20 meeting.
Still, economists predicted the Fed would raise rates 25 basis points to 1.25-1.50 percent in December. All 100 economists polled expect it to keep policy on hold at its next meeting.
The central bank is projecting three more rate increases in 2018, while economists expect only two next year, which would take the fed funds rate to 1.75-2.00 percent.
But about two-thirds of 52 economists who answered an extra question said risks to those forecasts were skewed more toward a slower pace of rate hikes. Fifteen of those respondents suspected there could be fewer than two increases next year.
The remaining 17 economists said there was a greater chance of faster rate hikes.
Economic growth probably took a hit from the devastation caused by Hurricanes Harvey and Irma.
The consensus in the latest Reuters poll was for an annualized expansion of 2.4 percent in the third quarter, down from 2.6 percent in last month's survey. Growth expectations for this quarter remained at 2.5 percent.
The median full-year forecast was 2.2 percent for 2017 and 2.3 percent for next year.
Predictions for core PCE inflation have not changed much from last month, with the consensus now in a 1.4-1.9 percent range through the end of next year even though the jobless rate has fallen well below 5 percent.
(For other stories from the Reuters global long-term economic outlook polls package) (Polling by Indradip Ghosh and Hari Kishan; Editing by Lisa Von Ahn)