The federal government maintains the largest fleet of vehicles of any organization in the nation.

One congressman sees that as an opportunity.

Over the last few years, Rep. Eliot Engel, D-N.Y., has introduced the same amendment to virtually every appropriations bill to make it to the House floor. The measure aims to stop agencies from buying cars and other light vehicles that rely on only gasoline.

Instead -- beginning in 2016 -- all new light-duty vehicles would be required to use alternative fuels, such as hybrid, electric, compressed natural gas or bio fuel. The conversion, Engel has said, would help agencies find savings and make the nation more secure.

“Our economy and our national security are threatened by our dependence on foreign oil,” Engel said. “Each federal agency possesses a fleet to which this could be applied.”

The Obama administration has consistently fought to regulate industries that negatively impact the environment, but has met time and again with pushback from congressional Republicans. Engel’s repeated victories, therefore, represent rare bipartisan agreement on environmental policy.

Most recently, Engel successfully attached the amendment to the 2015 Financial Services and General Government Appropriations Act, marking the 11th time it has been approved since Engel began his campaign. Congress has rarely passed regular appropriations in recent years, however, so the legislation has not yet been signed into law.

President Obama issued a presidential memorandum in 2011 with the same goals Engel is pushing. Those benchmarks -- requiring all new light-duty vehicles to be alternatively fueled by Dec. 31, 2015 -- could be overturned by a future administration, however, motivating Engel to continue his crusade. The New York congressman has so far successfully amended four fiscal 2015 spending bills to include his federal fleet language. He’s also pushed legislation that would set alternative fuel standards on all vehicles sold in the United States.

The federal government maintains a fleet of more than 630,000 vehicles, which comes with an annual price tag of more than $4.4 billion.