WASHINGTON — Minnesota Democrats are feisty and fired up as they head to their party's 2004 convention, but there's no disguising what a bleak four years this has been for them. The last time Minnesota's Democratic-Farmer-Labor delegates gathered at a national convention, back in the millennium summer of 2000, they buzzed with energy from U.S. Sen. Paul Wellstone, U.S. Rep. Bruce Vento, and party co-chair Mary McEvoy —now all deceased.