Those supporting the amendment, which passed on a 62-37 vote, said it would save lives and money.
“Our military is on the cutting edge technologically, but much of our fighting capability relies on foreign fossil fuels and decades-old power systems. That dependence has very real human and economic costs. Today’s strong bipartisan vote affirms that we should allow our military leaders to continue to develop and use advanced alternative fuels in order to bring down costs and improve mission capabilities," Udall said in a Wednesday statement.
Inhofe argued that biofuels are too expensive, with $500 billion of defense cuts slated for the next 10 years as part of sequestration.
Inhofe, along with other Republicans, opposes using military spending to commercialize energy technology, though several senators argued the Defense Department has a history of investing in less mature energy sectors.
Still, Inhofe said biofuels are something the Department of Energy should be spending money on, not the Department of Defense.
“This is something [the Department of Energy] should be doing if anybody is going to be doing it,” Inhofe said on the floor Wednesday. “This one amendment, more than any other, would take money away from readiness.”
But the amendment's Senate proponents said biofuels could help keep military energy spending down by reducing the military's exposure to oil price shocks.
The program has the support of Defense Secretary Leon Panetta and Navy Secretary Ray Mabus, who also contend it would stabilize energy costs. They call the program vital for energy security, saying it gives the military more fuel options and loosens it from foreign oil’s grip.
Sen. Barbara Boxer (D-Calif.) asked if the Senate has to once again have a fight about oil.
“Is big oil calling the shots here?” Boxer said Wednesday before the vote. “I would hope not, but I don’t understand why this section Sen. Udall is trying to strike is in this bill when the military says it’s critical to them.”
Republican senators voting with Democrats to approve the amendment included Sens. Roy Blunt (Mo.), Thad Cochran (Miss.), Susan Collins (Maine), Chuck Grassley (Iowa), John Hoeven (N.D.), Dick Lugar (Ind.), Lisa Murkowski (Alaska), Olympia Snowe (Maine) and John Thune (S.D.). Democratic Sens. Joe Manchin (W.Va.) and Jim Webb (Va.) voted against the amendment.
Collins, who serves on the Armed Services Committee, missed the May committee vote on the Inhofe amendment, which passed by one vote.
The Truman National Security Project's Operation Free campaign, which aims to wean the U.S. off oil, praised the Senate for passing the amendment.
"Our dependence on oil as a single source of transportation fuel endangers our national and economic security. We spend billions of dollars every year securing strategic chokepoints in the global oil supply line, and any rise in oil prices leaves the DoD on the hook for millions or even billions in additional fuel costs," Mike Breen, executive director of the Truman National Security Project, said in a Wednesday statement.
Biofuels groups said the vote showed the nation is committed to alternative fuels.
"Reports of the demise of biofuels political currency appear to be premature. Americans clearly support reducing our dependence upon foreign oil and strengthening our national and economic security via domestic renewable fuels," Renewable Fuels Association CEO Bob Dinneen said in a Wednesday statement.
— This story was last updated at 11:59 a.m. Thursday.