Newt Gingrich won the highest grade from the Iowa Corn Growers Association in its ranking of Republican presidential candidates on agriculture issues.

Newt Gingrich

Herman Cain and Rep. Ron Paul, R-Texas, were at the bottom of the list.

The association, in releasing its rankings Wednesday, said it is not endorsing any of the candidates but sent surveys to the presidential hopefuls to assess their positions on the issues. If the candidates didn’t respond, the group said, it studied their public statements, records and websites.

“Iowa is in a unique political position because of our first-in-the-nation status,” Kevin Ross, a farmer from Minden and the association’s president, said in a statement. “This gives corn growers the opportunity to have real input in the development of the presidential candidates’ positions on agricultural policy.”

The group studied issues related to energy policy, farm programs, trade, water infrastructure and Environmental Protection Agency regulations. It ranked candidates from “A” to “F” in relation to the group’s legislative priorities.

Gingrich, the former House speaker, was given “A” grades across the board.

Next was former U.S. Sen. Rick Santorum of Pennsylvania, whose only difference from Gingrich was on conservation programs. Santorum scored a “C” on that part of the score card but got an “A-” overall.

Mitt Romney was given a “B” grade. He rated highly on energy issues but scored lower on the part of the survey measuring positions on farm programs. There also were areas where his position was unclear, the report card said.

Texas Gov. Rick Perry, who has said he would end ethanol subsidies, got a “C-minus” grade.

U.S. Rep. Michele Bachmann, R-Minn., got a “D+” grade overall, scoring lower on part of the survey related to energy and farm programs.

Cain and Paul got “D” grades overall. Cain got “F” grades in all areas except those that related to trade, regulations and water infrastructure, where he was given “A” marks.

Paul, who has spoken out against energy subsidies as well as a large chunk of federal spending, scored poorly on parts of the survey related to farm programs, trade and water infrastructure.

President Barack Obama also was given a grade by the group. He rated a “B” overall. He got “A” and “B” grades for much of the survey but scored a “C” in the part pertaining to regulation and oversight.

The project was done in conjunction with the National Corn Growers Association and is called the Corn Caucus Project Presidential Report Card. The Iowa group has more than 6,700 members.