Republican presidential nominee Mitt Romney branded the Federal Reserve's new economic stimulus effort a "sugar high" Friday, telling donors that the latest U.S. monetary easing will cost Americans.

The Fed announced its bid Thursday to help speed up growth and reduce joblessness by buying $40 billion per month worth of mortgage-backed securities, as it pledged to keep its benchmark interest rate at ultra-low levels until at least mid-2015.

It was the Fed's third quantitative easing program in less than three years, and Romney said he did not expect "QE3" to work.

Romney, who trails President Barack Obama slightly in national polls ahead of the November 6 election, has long said on the campaign trail that his plan to boost energy and trade, improve education, slash federal spending and champion small business would bring the U.S. economy roaring back.

Under a Romney presidency, "we're not going to have to look for the sugar high that comes with QE3 or QE4 or QE5 or QE6," he told donors at a fundraiser before flying to battleground state Ohio, where he holds a campaign rally.

"Recognize that as the Federal Reserve keeps on trying to stimulate the economy by printing more money, that there's a cost to that," Romney told several hundred supporters, some of whom paid as much as $25,000 to have breakfast with the Republican nominee at a New York hotel.

"The value of your savings goes down. People who are living on fixed incomes don't see much interest income any more, and the value of the dollar goes down and the risk for long-term inflation goes up," he added.

"The real course ahead for America is to encourage the growth of our economy, not just to go out there and print more money."

Romney has said that the Fed's first two rounds of quantitative easing have not produced results, while leaving the economy vulnerable to a return to high inflation.

Fed Chairman Ben Bernanke said the new monetary easing effort would remain in place until it sees substantial improvement in the US jobs market, where 8.1% of Americans remain unemployed.

Earlier Friday Romney told ABC television that QE3 showed Bernanke at odds with Obama over the rate of U.S. economic recovery.

"The president's saying the economy's making progress, coming back. Bernanke's saying 'No, it's not. I've got to print more money,'" Romney said.

"I don't think what Bernanke is doing is going to get the economy going," he added. "I think we have to have a leadership in Washington that encourages the private sector."

Romney also reiterated his position that he would replace Bernanke if he wins the election.

Copyright Agence France-Presse, 2012