The Houston mega-pastor Kirbyjon Caldwell—who presided over Jenna Bush's wedding last month and has offered spiritual counsel to her father—is a Christian VIP, so busy that his cell-phone voicemail says, "Do not leave messages here." But on Friday mornings, whether he's at church, in the car or on the golf course, Caldwell tries to dial into a certain highlevel conference call. At 9:30 Eastern time, a group of religious leaders gathers "telephonically," as Caldwell puts it; for 15 minutes, they pray for Sen. Barack Obama....