A broad coalition of liberal public policy groups said yesterday it has initiated a campaign against the selection of John Ashcroft to be Attorney General. The plan to defeat Ashcroft, a former Republican senator from Missouri, was announced as spokesmen for the coalition said the effort would be the largest ever mounted against a cabinet selection. The groups denounced Ashcroft’s Senate record as extreme and placed Ashcroft at the conservative fringe of his party. Among the positions the coalition condemned were Ashcroft’s opposition to abortion, gay rights and gun control, and his support for the death penalty and the elimination of the National Endowment for the Arts. Ralph Neas, president of People for the American Way, said, “This is the worst executive branch nomination I have ever seen.” The confirmation hearings will begin next Tuesday. One of the first witnesses against Ashcroft is likely to be Justice Ronnie White, the first black justice on the Missouri Supreme Court, who was denied a federal judgeship largely through the efforts of Ashcroft.