Investors and economists have become far more skeptical over the past two weeks that the U.S. Federal Reserve will announce a new round of bond purchases at its September meeting, according to Reuters polls over the last week.

While hardly portraying a surging economy, U.S. economic data over the last two weeks have, for the most part, come in a little better than forecast.

That has persuaded many economists and fund managers a new round of monetary easing from the central bank is no longer a safe bet, although polls of both groups suggest the result of its September policy meeting will be a close call.

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did

Only 44 percent of fund managers in the Reuters global asset allocation poll published Thursday now think the Fed will announce a third round of quantitative easing, down from 70 percent in the same poll last month.

Similarly, a poll of economists last Friday gave a 45 percent chance of a new round of quantitative easing resulting from the Fed's Sept. 12-13 policy meeting, a sharp cut from 60 percent in another poll earlier in the month.

Fed Chairman Ben Bernanke will give a much-awaited speech on Friday at Jackson Hole, Wyoming, at the central bank's annual retreat. Many investors are hoping for a clear signal, as he famously did two years ago, that he will print more money.

But they may have their hopes dashed.

"I think he is going to leave his options open," said Gary Schlossberg, senior economist at Wells Capital Management, which has more than $325 billion in assets under management.

"It's going to be similar in tone to the (Federal Open Market Committee) minutes, and the markets will be disappointed."

Minutes from the Fed's July 31-Aug. 1 meeting suggested it was likely to deliver a new round of monetary stimulus "fairly soon" unless the economy improved considerably.

But recent economic data may have changed the picture, even since last Wednesday's publication of the minutes. Consumer spending data are improving and there are signs the battered U.S. housing market may have turned the corner.

"We don't believe that economic conditions justify any further action by the Fed," said David Goerz, chief investment strategist at HighMark Capital Management in San Francisco.

"The minutes are a bit dated at this point, given a lot of the data released since the Fed's last meeting."

The U.S. economy grew a little faster than thought in the second quarter, although not enough to close the door on more bond purchases, which so far total $2.3 trillion. Jobs growth also remains weak, despite a rebound in July.

That has brought the Fed's performance under political scrutiny ahead of the Nov. 6 presidential election, particularly among opposition Republicans who have criticized quantitative easing as an inflation time bomb.

Monica Defend, head of global asset allocation at Italy-based Pioneer, said that is one main reason why the Fed will not launch a new round of bond purchases before the end of the year.

"The presidential elections are coming up in November and any (policy) move may not be recommended until the January inauguration," she said.

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did