With hopes for U.S. potatoes to be allowed into the heart of Mexico dashed last fall when Mexican officials backtracked on previous plans to loosen regulations, U.S. Sen. Dianne Feinstein, D-Calif., is urging America’s trade representative Ron Kirk to continue his work to harmonize trade standards.

Feinstein sent a letter to Kirk in February specifically discussing what she described as “unscientific barriers to trade.”

Feinstein cited an agreement signed in 2003 that was supposed to grant U.S. fresh potatoes access into Mexico beyond the border zone by 2004.

Feinstein said in the letter that the limited access for U.S. potatoes is costing the industry $100 million annually in lost export opportunities.

As of early March, the Mexican government had not issued any new statements about the situation.

John Keeling, National Potato Council executive vice president, continues to maintain a positive outlook on the final outcome of the trade negotiations but does not expect resolution soon.

Keeling predicted it will be a long battle with a lot of back and forth, like a chess game. He describes the situation as a policy fight between two cabinet level agencies in Mexico

“We think in the end that this thing has risen to very high levels in both governments and we’re very comfortable with the discussion happening in that way,” Keeling said.