If McCain loses CO and the rest of the 2004 map stays the same, he can afford to lose one of either NM, NV, or IA. But he must hold VA. If he loses CO, plus more than one of NM, NV, or IA, he needs PA. If he loses CO and just VA, he needs PA. If he loses CO, NM, IA, and VA, he can still win with PA. If he loses CO, NM, IA, NV, and VA, he loses even with PA.