Congress is expected to remain in session beyond Thanksgiving and into December, but a TRIA extension joins a host of must-do and controversial bills Congress must deal with before it departs.

"State legislatures applaud the efforts of Congressional leaders and the administration in pursuing reforms that will promote the development of the private terrorism insurance market and recognize the temporary nature of the program," the NCSL letter said.

"NCSL believes that some reforms can and should be included in a short-term extension, but a permanent solution that effectively transitions to a market-based system founded on effective terrorism pricing models and private sector capacity will take study and deliberation, which the pending expiration does not allow," the letter added.

"We also believe that TRIA should be extended cleanly and not used as a vehicle for other more controversial measures that will weigh it down and risk exposing our nation's economic security," it said.