NEW YORK, Sept 17 (Reuters) - U.S. lawmakers from both sides of the aisle spoke out on Thursday against the potential use of Department of Agriculture funds to bail out refiners that are denied exemptions from the nation's biofuel blending laws.

Reuters reported on Wednesday that the Trump administration is considering at least $300 million in financial relief to refiners denied waivers from the U.S. Renewable Fuel Standard, requiring them to blend biofuels like ethanol into their fuel or purchase credits, for the 2019 compliance year. The money could come from funds within the USDA, five sources familiar with the matter told Reuters.

The idea irked the lawmakers because USDA funds are meant to help farmers, not the oil industry.

U.S. Senator Debbie Stabenow of Michigan, a Democrat, called the idea "outrageous" during comments on the Senate floor on Thursday, and accused the Trump administration of siding with oil companies over farmers repeatedly.

Stabenow has been part of a push to highlight Democratic presidential candidate Joe Biden's commitment to farmers. She helped lead a press call this week organized by Biden's team that spoke in support of the former vice president's approach to biofuels.

Meanwhile, Senator Chuck Grassley, a Republican from Iowa, said USDA funds were meant for struggling farmers. "It's not a surprise that Big Oil is looking elsewhere for government handouts," Grassley spokesman Michael Zona said in a statement.

The bipartisan criticism comes as both Trump and Biden's campaigns court votes across the Midwest ahead of Nov. 3's presidential election by showing support for the biofuel industry. Trump's Environmental Protection Agency recently rejected scores of retroactive refinery waiver requests, which biofuel producers say threaten demand for their products.

Refiner groups have also criticized the possibility of cash aid to refiners denied waivers, saying the administration should instead focus on improving elements of the Renewable Fuel Standard.

White House and EPA officials did not comment. (Reporting by Stephanie Kelly; editing by Jonathan Oatis)