WASHINGTON (Reuters) - The U.S. Environmental Protection Agency said on Tuesday that it will soon have a decision on whether to waive the mandate that requires blending billions of gallons of corn-based ethanol into the national gas supply each year.

"EPA is completing its review and analysis of the RFS waiver requests and the agency plans to reach a decision shortly," an agency spokeswoman said, referring to the ethanol mandate or Renewable Fuel Standards.

Aimed at reducing U.S. reliance on foreign oil, the RFS requires 13.2 billion gallons of ethanol to be made from corn this year.

In August, several governors asked the EPA to temporarily waive the mandate on ethanol because the worst drought in 50 years has driven corn prices higher and hurt livestock producers who depend on the grain for feed. Forty percent of the U.S. corn crop is used to make ethanol.

A decision on the waiver is expected by the end of the month.

In 2008, EPA denied a request from Texas to relax the mandate during a period of surging corn prices. Ethanol trade groups say they expect the same ruling this time.

(Reporting By Patrick Rucker; editing by Carol Bishopric)