The chairman of the House Financial Services Committee questioned on Tuesday the usefulness of the Federal Reserve's forward guidance tool—ahead of new Fed Chair Janet Yellen's testimony to the panel.
Central bank policymakers have been trying for months to play down the importance of the amount bond buying, which has undergone two rounds of tapering, in favor of projecting where interest rates will be in the foreseeable future.
In her prepared remarks, Yellen said it's likely the Fed will have to keep rates near zero "well past the time" that unemployment crosses below the 6.5 percent threshold, which had been set more than a year ago as benchmark for possible monetary tightening. The jobless rate was at 6.6 percent in January.
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"What good is forward guidance if when you reach a milepost you jettison it?" asked Rep. Jeb Hensarling on CNBC's "Squawk Box."
"There are exceptions to every rule, but at some point you have no rule. You're making it up as you go along. And I think that breeds greater fear and uncertainty in the capital markets."
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Questioning extraordinary measures the central bank has used in the name of supporting the economy and whether it's worked, the Texas Republican said, "This isn't your father's Fed."
The Hensarling interview was conducted before the release of the prepared text of Yellen's testimony. She also said she expects a great deal of continuity from Ben Bernanke's stewardship, during which she served as No. 2 at the Fed.
Meanwhile, Jim Paulsen, chief investment strategist at Wells Capital Management, told CNBC that he'll be looking for any signs that the pace of Fed tapering may slow down. "That could be influential [on Wall Street] in the short term."
But he added, "The Fed is going to be largely less relevant than people think this year," unless in the unlikely event that inflation concerns surface.
—By CNBC's Matthew J. Belvedere. Follow him on Twitter @Matt_SquawkCNBC.