A bipartisan group of 39 senators called on the Environmental Protection Agency Friday to strengthen the 2017 Renewable Fuel Standard for biofuels in the nation's gasoline supply.

Led by Sens. Chuck Grassley, R-Iowa, and Amy Klobuchar, D-Minn., the senators urged the EPA to increase the amount of biofuel in the nation's gasoline in order to support jobs in their states. The agency proposed adding 18.8 billion gallons of renewable fuel, mostly corn ethanol, to gasoline in 2017 in the newest Renewable Fuel Standard announced.

The letter argued the EPA has set the biofuel standard back in recent years by not raising biofuel levels.

The oil industry has often argued that the American automobile sector is not set up to handle more ethanol in fuel, and says a higher percentage of ethanol in gasoline could harm car engines. According to the oil industry, car engines will be damaged if more than 10 percent of the nation's gasoline supply consists of ethanol.

However, that means biofuel projects are moving overseas, the senators argued.

"We cannot afford to cede our leadership position in the world," the letter stated. "A strong RFS, and more biofuels, make our country more secure. It increases competition and choice, strengthening our economy."

"We urge you to take the opportunity to get the program back on track by setting blending targets where Congress intended and by removing the distribution waiver."

In the 18.8 billion gallons of biofuel the EPA plans to require to be added to gas in 2017, 14.8 billion are conventional biofuels, mostly corn ethanol. That's below the level established by Congress for 2017 and the senators want that to change.

"We urge you to ensure that the final rule promote growth in the U.S. biofuel sector and capture economic opportunity rather than drive investment overseas," the letter stated.

The letter received praise from ethanol groups that want to see the standard strengthened in 2017.

Bob Dinneen, president and CEO of the Renewable Fuels Association, said a stronger standard would get the program back on track. The EPA has been lowering amounts in order to cater to energy industry interests and that needs to stop, he said.

"We thank the lawmakers for their leadership to ensure EPA finalizes a strong RFS that gets the program back on track," Dinneen said. "In proposing a lower conventional biofuel target for 2017, the EPA is catering to the oil industry by relying upon an illegal interpretation of its waiver authority and concern over a blend wall that the oil industry itself is creating."