Retired General Wesley Clark isn`t at the top of every poll, but he`s not too far behind. A poll of Michigan voters, released yesterday, shows former Vermont Governor Howard Dean pulled into the lead of the Democratic presidential field, with 21 percent support. The state`s Democratic caucuses are in February. Behind him was Clark of Little Rock, at 15 percent. Congressman Dick Gephardt of Missouri and Senator John Kerry of Massachusetts had 13 percent, and Senator Joe Lieberman had 12 percent. The poll was conducted Monday through Thursday. Considering the poll`s margin of error, the four were essentially tied for second place. The poll was the first to show anyone with a lead in Michigan over the other Democrats in the race.