IRAQ HAS BEEN a vexing issue for John Kerry. Every time he takes a position, the domestic political ground seems to shift under his feet. He supported the use-of-force resolution in 2002, only to find that Democratic audiences hated the war and were flocking to Howard Dean. So Kerry adjusted his rhetoric to sound more like the Vermont governor. Then, once assured of the nomination, he began tacking back to the center to court moderate, general-election voters. Now, just as much of the country is moving left on the war, Kerry has moved right.