The housing industry’s largest groups are joining the fight against the federal government’s practice of using funds raised from Fannie Mae and Freddie Mac’s guarantee fees to cover federal spending.

Earlier this week, bipartisan group of senators, led by Sen. Mike Crapo, R-Idaho, and Sen. Mark Warner, D-Va., announced a budget point of order that would prevent G-fees from being used to offset federal spending, a practice the Senators call a “budgetary gimmick” and a “back door tax” on homeowners.

On Wednesday, the American Bankers Association, American Land Title Association, Credit Union National Association, Financial Services Roundtable, Housing Policy Council, Leading Builders of America, Mortgage Bankers Association, National Association of Federal Credit Unions, National Association of Home Builders, and National Association of Realtors sent a letter to the leaders of the U.S. Senate Committee on the Budget expressing their support Crapo and Warner’s bill.

“G-fees are a critical risk management tool used by Fannie Mae and Freddie Mac to protect against losses from faulty loans, and should be used only to manage the companies’ credit risk,” the groups said in the letter addressed to Sen. Michael Enzi, R-Wy. and Sen. Bernie Sanders, I-Vt.

“Increasing g-fees for other purposes effectively taxes potential homebuyers and consumers wishing to refinance their mortgages,” the groups continued. “G-fee increases unrelated to housing could also act to hinder the necessary reforms required of the housing finance system in the years ahead.”

According to a release from Warner’s office, each time the g-fees are increased and diverted for unrelated spending by Congress, taxpayers are “left exposed to additional risk and homeowners ultimately incur the cost in their mortgage bills.”

In addition, the more guarantee fees are used as offset, the harder it will become to implement much-needed reforms to the nation’s housing finance system because it increases the price tag of any legislation, Warner’s office said.

“Congress must get serious about reforming Fannie and Freddie and stop treating them as political entities,” Crapo said this week. “Any increase of guarantee fees should be used to protect taxpayers from mortgage losses — not used as an artificial offset for new government spending.”

The bill, S. 752, is co-sponsored by Sens. Richard Shelby, R-Ala., Jon Tester, D-Mo., Bob Corker, R-Tenn., Heidi Heitkamp, D-N.D., David Vitter, R-La., Joe Donnelly, D-Ind., Mark Kirk, R-Ill., Dean Heller, R-Nev., Tim Scott, R-S.C., and Jerry Moran, R-Kan.

“We are united in our belief that using g-fees as a funding mechanism places an unnecessary burden on homeowners and prevents Fannie Mae and Freddie Mac from effectively managing their risk, and urge the Budget Committee to pass the amendment offered by Senators Crapo, Warner, Corker, and Merkley,” the housing groups said in the letter.