The lawmakers sent a letter on Tuesday to Federal Communications Commission Chairman Julius Genachowski, citing the government's commitment to free up more spectrum for mobile services. LightSquared had planned to launch a land-based LTE (Long-Term Evolution) network that would complement its slower satellite mobile system, but in February the FCC took steps to that plan. Tests last year had shown interference between the LTE system and GPS (Global Positioning System). LightSquared last month.

"We ask the FCC to conduct a thorough and thoughtful review of all available spectrum controlled by the Department of Defense (DoD) that could be repurposed or reallocated to meet increased demand," the letter said. "We also request that the FCC move swiftly to identify other options, including the use of alternate spectrum, for LightSquared's proposed nationwide 4G LTE wireless broadband network."

"A spectrum swap is the most resourceful and efficient way to quickly expand broadband access nationwide," the letter said.

The letter was signed by Democrats Jim Moran of Virginia, Maurice Hinchey of New York and Steve Rothman of New Jersey, as well as Republicans Rodney Alexander of Louisiana and Ander Crenshaw of Florida.

Politics has become a recurring theme in LightSquared's efforts to get its network off the ground since it received conditional approval from the FCC in January 2011. LightSquared has been accused of using campaign contributions to win an easy pass from the Obama Administration, and the FCC has been accused of about its dealings with the company. Both LightSquared and its opponents in the GPS industry have heavily lobbied lawmakers along the way.