By pandering to another interest group, the AFL-CIO, the Democratic presidential candidates on Tuesday made it more difficult for one of them to oust President Bush next November. With three momentary exceptions when Sens. Joe Lieberman (Conn.) and Bob Graham (Fla.) showed some courage and independence, the nine candidates fell all over themselves to tell the trade union convention in Chicago exactly what it wanted to hear on every issue. In the process, candidates-Sens. John Kerry (Mass.) and John Edwards (N.C.)-abandoned previous positions in favor of free trade, an idea that is popular with Americans almost everywhere but at the...