Over 30 percent of the Republicans who participated in South Dakota's presidential primary last week voted "uncommitted." For Republican voters in Maryland today that is not an option. Only George Bush and Pat Buchanan are on the ballot. Democrats not satisfied with their choices may, however, pull a lever for "uncommitted to any presidential candidate." Few exercise this option. Last time, only 2.5 percent did. But Democrats who strongly disapprove of their listed choices and are unfamiliar with uncommitted delegate candidates do have a way of showing that disapproval.