Minutes from the Fed's March meeting released this month showed support thinning for further bond purchases. Officials are unlikely to develop any more appetite for them by their meeting next week, despite disappointing March jobs figures.

Policymakers have been heartened by patches of better economic data that raised hopes for solid growth this year, which helps explain their reticence toward further monetary stimulus.

"The state of the economy doesn't argue for them to do more stimulus but it also doesn't warrant them doing less," said Ann Owen, a former Fed economist now at Hamilton College in Clinton, New York.

Officials are also leery of a barrage of anti-bond-buying sentiment both at home and abroad, with Republicans criticizing the Fed for weakening the dollar and developing countries arguing that the weaker currency gives U.S. exporters an unfair advantage.

Even within the Fed, hawks are making plenty of noise, not only about the possible detrimental effects of further quantitative easing, but also about the likely need to begin raising interest rates soon. For some, that means within months.

"A number of officials are very vocal in their expectations of tighter policy sooner than later," said Tim Duy, an economics professor at the University of Oregon and author of a popular blog on the Fed. "I don't think they would be so vocal if they thought there was likely to be a policy shift (in the opposite direction) in the near term."

That minority chorus diverges sharply from the broader message coming from the policy-setting Federal Open Market Committee. Officials will likely hold to that message at their April 24-25 gathering: official borrowing costs look set to remain near zero until at least late 2014.

That is a timetable Janet Yellen, the Fed's influential vice chair, staunchly defended in a speech last week. Her strong support for Fed rates guidance, the latest step in an effort to increase policy transparency, suggests the central bank may rely in shifting that goalpost back and forth as its primary policy tool until it decides on more decisive action - either further asset purchases or the start of a policy tightening.

The latest Reuters poll of primary dealers - banks that do business directly with the Fed - found that 11 of 15 still believe the central bank eventually will resort to a third round of bond buys or, in market parlance, QE3.

The U.S. economy expanded at a 3 percent annual rate in the last three months of 2011 but is expected to have slowed in the first quarter. Unemployment came down rather quickly, from 9.1 percent last summer to 8.2 percent in March, yet analysts and Fed officials believe further progress will be tougher to achieve.

BELLS AND WHISTLES

With interest rates close to zero, the Fed has - as one trader put it - come to rely on a lot of "bells and whistles" to influence the economy.

The April meeting is a case in point. The Fed will release its usual policy statement at noon, likely making only small tweaks to its assessment of the economic backdrop.

It will then release an update of its quarterly economic forecasts, as well as an outline of policymakers' individual estimates for when interest rates should be raised.

In addition, Fed Chairman Ben Bernanke will hold a news conference at which he will be bombarded with questions about the prospect for further easing.

He is likely to keep his options open. The Fed appears to be taking a wait-and-see approach, trying to gauge whether the relatively brighter economic signs of recent months prove lasting.

The central bank's subsequent policy meeting in June may prove more critical. Its most recent effort to keep down long-term rates by selling short-term securities and buying longer dated ones is set to expire at the end of June.

Atlanta Federal Reserve Bank President Dennis Lockhart, a policy centrist and 2012 FOMC voting member, told reporters last week the Fed would watch the bond market closely as the program ends to see if yields are pressured higher. But he added that the bar remains high for another round of monetary easing.

(Reporting by Pedro da Costa; Editing by Dan Grebler)

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