The letter was sent in the midst of a two-day meeting in which Fed officials are widely expected to undertake policies to lower long-term interest rates. That move would be intended to loosen up credit in hopes of promoting growth. The meeting ends Wednesday, and the Fed is expected to release a statement Wednesday at 2:15 p.m.

“We have serious concerns that further intervention by the Federal Reserve could exacerbate current problems or further harm the U.S. economy,” said the letter, signed by four of the top Republicans in Congress: Mitch McConnell of Kentucky, the Senate Republican leader; Jon Kyl of Arizona, the Senate Republican whip; House Speaker John Boehner of Ohio and House Majority Leader Eric Cantor of Virginia…

“I just don’t think the Fed will sit idly as momentum fizzles in this recovery,” said Dana Saporta, a United States economist at Credit Suisse.