WASHINGTON — A Washington, D.C., watchdog group is seeking records from the Environmental Protection Agency to determine if political pressure from oil interests led to the agency’s decision to scale back the amount of renewable fuels that must be blended into the nation’s transportation-fuel supply.

Citizens for Responsibility and Ethics in Washington (CREW) on Wednesday filed a request for internal EPA records concerning its Renewable Fuel Standards for 2014.

Specifically, CREW is trying to determine if Delta Air Lines and the Carlyle Group, which own two refiners in the Philadelphia area, enlisted “undue influence” — from people including Vice President Joseph Biden and Gene Sperling, President Obama’s former top economic adviser — to force the EPA to back down on renewable-fuel mandates.

In November, the EPA for the first time proposed a year-over-year decrease in the amount of renewable fuels that must be added to petroleum-based fuels. The agency also proposed keeping the mandate for a subset category, biodiesels, unchanged at 1.28 billion gallons for two more years.

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That latter decision upset biodiesel producers in Seattle and around the country, who had been expecting a 33 percent increase to 1.7 billion gallons instead. Seattle-based General Biodiesel has already cut back production by 20 percent and reduced workers’ hours.

The federal government essentially sets the size of the market for renewable fuels, through blending mandates and tax subsidies.

CREW’s Freedom of Information Act request was prompted by a Reuters report earlier this month that two Pennsylvania congressmen, Reps. Patrick Meehan and Robert Brady, enlisted members of the Obama administration to lean on the EPA on behalf of Carlyle and Delta.

Higher requirements for use of renewable fuels drive up costs for refiners.

Derrick Crowe, a spokesman for CREW, said the records request was made in hopes that it “can help clarify whether the EPA made decisions … in the public interests or to protect oil refinery interests.”

Last week, CREW asked the EPA’s inspector general to investigate as well.

Jeff Haas, chief executive of General Biodiesel, said the EPA’s proposal to backtrack on the renewable mandate was “inexplicable.”

Haas said the EPA’s action undercuts the Obama administration’s own embrace of alternatives to fossil fuels and defies warnings in the third National Climate Assessment report.

“Political pressure is the leading suspect,” he said.

Haas’ company converts used cooking oil — collected free from Ivar’s restaurants as well as restaurants at CenturyLink Field and Seattle-Tacoma International Airport and elsewhere — into biodiesel that is blended with petroleum diesel.

Only one other company based in Seattle currently is producing biofuels: Imperium Renewables, which uses oils from canola, soy and other crops at its facility in Grays Harbor County.

The EPA has said the lower overall mandates for renewables were driven in part by ethanol producers hitting a “blend wall” that limits production.

But Haas said he does “not buy the EPA’s statement that its decision was based on production and infrastructure concerns.” What’s more, he said, any issues with ethanol are unrelated to biodiesel producers, which in 2013 churned out 1.7 billion gallons, exceeding this year’s proposed cap.

The EPA’s 2014 Renewable Fuel Standards are expected to be finalized in June.

Kyung Song: 202-383-6108 or ksong@seattletimes.com. Twitter: @KyungMSong