The overwhelming majority of Democratic leaders who are automatic delegates to next summer's national convention have no clear idea whom they want as the party's 1988 presidential nominee, according to an Associated Press delegate survey. Democratic delegates who are uncommitted--278--outnumber those with an early candidate preference by nearly 4 to 1. The leader among the candidates, Massachusetts Gov. Michael S. Dukakis, has lined up just 23 delegates who will cast 22.5 votes at the convention. The survey found that Missouri Rep. Richard A. Gephardt has 13 votes, followed by Illinois Sen. Paul Simon, 12, Sen. Albert Gore Jr. of Tennessee, 10.5, the Rev. Jesse Jackson, 9.8 and former Arizona Gov. Bruce Babbitt, 4.