Housing groups have lobbied hard for extending federal loan limits, but their efforts may not succeed.

The National Association of Realtors (NAR), Mortgage Bankers Association and the National Association of Home Builders have stepped up their lobbying efforts to Congress in recent weeks to fight the planned expiration of the federal loan limit size increase – yet members of Congress seem unconvinced.

Originally passed in 2008, the federal loan ceiling was raised to $729,750 in an effort to provide mortgages to a greater variety of homeowners in more expensive markets. Since the housing bubble burst, banks have been notoriously stingy with their credit, and Fannie Mae and Freddie Mac have gone on to back nine out of 10 new home loans.

But with the federal limit set to decrease to $625,500 on Oct. 1, Ron Phipps, the president of the NAR, is warning that quite a few local home markets would be impacted by the measure. In a letter to a Senate Committee last week, Phipps wrote that 670 counties in 41 states would be affected by the declining limits, not just residents of New York and San Francisco.

In addition to words, the NAR and other groups have been using their checkbooks. Last year alone, housing groups spent $65 million on lobbying efforts, with the NAR leading the pack with $17.6 million in spending. Indeed, as the Wall Street Journal notes, few lobbying blocs possess the clout of housing, making the extension’s apparent defeat all the more puzzling.

And certain lawmakers do seem unconvinced of the extension’s importance. The Obama Administration has supported the declining limits, and has released no word that it will consider changing its mind. Diane Feinstein, a Democratic senator from California and powerful member of the Senate Appropriations Committee, has written no amendments to support the extension, and Richard Shelby, a Republican senator from Alabama, has openly opposed any further federal assistance for housing.

Federal support of the mortgage market has “done a lot of damage,” Shelby said. “I hope we wouldn’t do any more.”