WITH THE indictment of Lewis Libby and possible indictment of Karl Rove, President Bush faces a fateful choice. Bush can adopt a bunker mentality and try to appease his base of social ultra-conservatives and military hawks who have brought him such grief. Or he can reach out to the broad mainstream, as he pretended to do when he ran as a ''uniter, not a divider" in 2000. Who would have predicted that the Bush machine would implode so spectacularly, on so many fronts simultaneously? -snip- If he were Bill Clinton, you would expect him to ''triangulate" -- forsake his own...