A confluence of forces provides an almost perfect opportunity for health reform this year. Not the perfect reform, perhaps, but one that would significantly improve a sadly flagging system. The only obstacle-a big one-is politics. Right now, congressional Democrats are pressing to reauthorize and expand children's health insurance as a way to jump-start a better system. This expansion has already incurred a veto threat, partly because of costs. Separately, some congressional Republicans have indicated serious interest in reforming the way the tax system subsidizes health insurance. The Democrats, in their turn, have reacted with a yawn.