Republican leaders of a U.S. House of Representatives transportation panel introduced a measure on Wednesday that would privatize the national air traffic control system, placing it under a private nonprofit group run by a range of stakeholders including airlines.

The measure, long-anticipated and controversial, was in a bill to authorize Federal Aviation Administration funding for six years and is seen by Republicans as a way to bring greater efficiency to commercial aviation and free the system now overseen by the FAA from budget uncertainties created by deficit reduction and partisan gridlock in Congress.

But the legislation’s future is uncertain, with Democrats either opposed outright to the privatization effort or poised to introduce their own counter-measure. Privatization is also opposed by Delta Air Lines Inc, which has warned that such a move could lead to higher costs for air passengers.

Congress may also have difficulty undertaking major legislation before the November election, when voters will decide which party controls the White House and Congress.

“Our system is incredibly inefficient and it will only get worse as passenger levels grow and the FAA falls further behind in modernizing the system,” said U.S. Representative Bill Shuster, a Pennsylvania Republican who chairs the House Transportation and Infrastructure Committee.

(Reporting by David Morgan; Editing by Chizu Nomiyama and Grant McCool)