That increase would help offset the $1.4 trillion in revenue that would be lost from cutting the corporate tax rate, another part of both the Senate and House plans.

Police Concerns

Chuck Canterbury, president of the Fraternal Order of Police, which represents 325,000 law enforcement officers nationwide, wrote a letter to congressional leaders on Tuesday.

"The FOP is very concerned that the partial or total elimination of SALT deductions will endanger the ability of our state and local government to fund these (law enforcement) agencies," said the letter, distributed to reporters.

Emily Brock, a director at the Government Finance Officers Association, said if SALT deductions were killed by Congress, voters could revolt. "Can you blame an individual taxpayer?" she asked. "They try to minimize their individual tax liability."

Those who want to curb the century-old SALT deduction argue it only motivates local governments to seek more tax increases and spend more money. "Maintaining the deduction encourages government overspending and taxation," argues the American Legislative Exchange Council, a nonprofit group of conservative state legislators and private activists.

Various other groups are fighting on Capitol Hill to defend the SALT deduction, such as the National Association of Realtors and the U.S. Conference of Mayors.

Brady's District

Steve Williams, chief financial officer for Conroe, Texas, said its rapid growth demanded new fire stations, schools, roads and public safety services.

Conroe is near Houston and in the congressional district of Republican Representative Kevin Brady, chairman of the House tax committee and a champion of restricting the SALT deduction.