Sen. Joseph Lieberman, speaking in that trademark sonorous baritone, utters a simple statement that translates into real trouble for Democratic leaders: "I'm going to be stubborn on this."

Stubborn, he means, in opposing any health-care overhaul that includes a "public option," or government-run health-insurance plan, as the current bill does. His opposition is strong enough that Lieberman says he won't vote to let a bill come to a final vote if a public option is included...