Two potential contenders for the 2012 GOP presidential nomination are in Des Moines on Tuesday to speak at a green energy trade show.

Newt Gingrich and Rick Santorum are set to address the Iowa Renewable Fuels Association annual summit. The group represents the state's ethanol and biodiesel producers.

The former House Speaker has the pre-lunchtime slot. Recent reports have suggested Gingrich is edging toward entering the race and plans to base his campaign out of Atlanta.

Santorum will speak from 4 to 4:30 p.m., shortly before the "door prize drawing," according to a copy of the schedule.

Support for ethanol subsidies is widespread in Iowa, even among Republicans. In past cycles, some candidates have run afoul of Iowa Republicans because of their stances on ethanol. When Sen. John McCain (R-Ariz.) ran for the nomination in 2008, he was typically given a frosty reception in the leadoff caucus state because of his opposition to the subsidies. He subsequently chose not to compete in Iowa.