Mickey Kaus at Kausfiles argues that Bush's sagging poll numbers actually hurt Hillary. Here's why:
The anti-war left may well tear the Democratic party apart, just as it did in 1968, if it can't get its way on the next presidential nominee. This would not necessarily be good for conservatives, though it should be. The reason it might not is that if the left succeeds in nominating a Gene McCarthy or George McGovern, it will tend to draw the Republicans leftward to compete for independent moderates. A Rudy Guiliani might, under such circumstances, look very attractive to the GOP, but his social liberalism would be anathema to conservatives.
If the left does not get its way, and causes a fracture in the party, an impotent Democratic opposition could induce complacency in the Republicans and lead them to nominate someone who lacks the principles to be a wise and good leader. This, some would say, is precisely what happened when Richard Nixon won the nomination and presidency in 1968.
Of course, the other possibility is that the left will lead the Democratic party, one way or the other, over the cliff, and the Republicans will by default establish a political hegemony that'll last for a generation. We'll see.