WASHINGTON (Reuters) - A group of 17 U.S. House Democrats on Monday are introducing legislation on Monday that would award $6 billion to the U.S. Postal Service (USPS) to buy tens of thousands of additional electric delivery vehicles. The bill sponsored by Representative Jared Huffman and seen by Reuters would require at least 75% of the new fleet be electric or zero-emission vehicles. Last month, the USPS said it was committed to having electric vehicles make up 10% of its next-generation fleet as part of its multibillion-dollar plan to retire its 30-year-old delivery vehicles, but could boost that if it received billions of dollars in government assistance. The legislation is backed by some key Democrats, including Representative Peter DeFazio, who chairs the Transportation and Infrastructure Committee, and Representative Carolyn Maloney, who chairs the Oversight and Reform committee that oversees USPS. The bill would also require no less than 50% of medium/heavy-duty vehicle purchases be electric or zero-emission through 2029 and all new USPS vehicles be zero-emission after January 2040. The USPS said last month it had awarded a $482 million contact to Oshkosh Defense to finalize production for the next-generation postal vehicles, rejecting a proposal from electric-vehicle maker Workhorse Group Inc, which met last week with the Postal Service to question its decision. The USPS did not immediately comment Monday on the legislation. Workhorse, whose shares were up 12% Monday, said it applauds “any efforts that support the Biden administration’s goal of expanding the government’s fleet of clean, non-combustion engine vehicles for the benefit of American taxpayers and the environment.” The contract, which could be worth more than $6 billion in total, allows for delivery of between 50,000 and 165,000 of the vehicles over 10 years. In January, President Joe Biden vowed to replace the U.S. government’s fleet of roughly 650,000 vehicles with electric models. Asked what it would take to buy 90% EVs, U.S. Postmaster General Louis DeJoy told lawmakers last month: “We don’t have the 3 or 4 extra billion in our plan right now that it would take to do it.”