After all, Bush is right: we liberals really do think of things like SCHIP as building blocks on the road to universal healthcare, don't we? It's hardly a big secret. And one should never underestimate the horror with which conservatives view "socialized medicine." They've fought it like crazed lemmings for decades, and they fight it even when it conflicts their own bottom-line interests. Big business, for example, should be rapturous at the idea of getting rid of its healthcare obligations, but even today, with healthcare costs skyrocketing and no end in sight, business groups are endorsing national healthcare only tentatively and in small numbers. (In 1994 they caved in to conservative pressure and didn't support it at all.) Why? Because even though national healthcare would help their earnings and remove a huge monkey from their backs, they genuinely and truly loathe socialized medicine. It's a step on the road to weakness and decay.
I can't think of any perfect analogy on the liberal side of things, but late-term IDX abortions come close. We've fought various versions of the Partial Birth Abortion Ban Act for years, despite the fact that it polls pretty well and the actual number of people affected by the ban is minuscule. Why do this, even though it's a political loser? One reason is that we (correctly, I think) view it as a first step in pushing public opinion in the direction of a flat ban on all abortions. That's what Bush says he thinks of SCHIP expansion, and I'll bet he's telling the truth. He says it's spinach, and he says the hell with it.