President Carter's 1980 campaign chairman, Robert S. Strauss, who was once Carter's special trade representative and later his Mideast peace negotiator, is expected to join the board of directors of Archer Daniels Midland Co. of Decatur, Ill., a major grain and soybean processor.

Nothing unusual in that. Lots of departing government executives are asked to sit on corporate boards and lend their Washington expertise to the corporate world. It's profitable work, as well. Strauss, a partner in a large Dallas law firm, reportedly will get as much as $57,000 a year from ADM and says he expects to sit on several such boards.

But there may be more to this particular directorship. Last year, according to the Minneapolis Tribune, ADM -- the largest U.S. manufacturer of ethyl alcohol (used in making gasohol) -- was lobbying for a tariff on imported alcohol.

The tariff reportedly was opposed by Carter's inflation adviser, Alfred E. Kahn, and by Reubin Askew, who was then his special trade representative, who believed it would violate an international trade agreement, discourage competition and add to inflation. But Dwayne Andreas, ADM chairman, who is close friend of Strauss, persuaded President Carter last October to drop administration opposition to the alcohol trade restrictions. The Tribune says he promised to announce plans for a $250 million ADM gasohol plant in Des Moines shortly before the November election.

The tariff was approved by Congress Dec. 3.

Strauss told the Tribune he had nothing to do with the Carter decision to support the tariff, but that he thought it was justified to protect the infant U.S. gasohol industry.