It is too soon to determine whether to dial down the Federal Reserve's massive bond-buying program, and the economic picture may not be clear enough to make that decision for another three or four months, an influential U.S. central bank official said.

New York Fed President William Dudley, a close ally of Chairman Ben Bernanke, said on Bloomberg TV that it was possible to taper down the $85 billion in monthly asset purchases by the fall "if the economy does better and if the labor market continues to improve" in the face of tighter fiscal policies.

"It really depends on how the economic outlook evolves... It's too soon to make that determination," Dudley said in an interview that took place Tuesday but aired Wednesday. "I think three or four months from now you'll have a much better sense of is the economy healthy enough to overcome the fiscal drag or not."

The comments reinforced a speech Dudley gave earlier on Tuesday in which he dampened speculation among investors that the central bank was preparing to reduce its unprecedented monetary stimulus. That speech boosted bonds and stocks.

At 10 a.m. EDT on Wednesday, Bernanke is set to testify before the U.S. congressional Joint Economic Committee. The chairman may shed more light on the thinking of the majority of the Fed's 19 policymakers.

If the Fed dials down the purchases, Dudley said, it is not "tightening" policy but merely "adding less stimulus."

The U.S. economy looks to be growing at a 2 percent to 2.5 percent growth rate, "a pretty good performance given the amount of restraint that we're seeing from the fiscal authorities," he said.

But "I'm uncertain about what's going to happen to the economic outlook in the near-term because I don't understand really well how the tug-of-war between the fiscal drag and the improving economy will work ... out over the next couple of months," he said.