Sen. Joseph I. Lieberman (Conn.) has once again inserted himself into the middle of an inflamed partisan debate, raising questions about his motives, his ego and his fickle allegiance to the Democratic Party, which forgave him after he supported Sen. John McCain (R-Ariz.) for president. Lieberman, a Democrat-turned-independent who caucuses with his former party, says he is feeling "relevant" as he threatens to withhold his vote -- potentially the decisive 60th -- on health-care reform legislation if it includes a government-run insurance plan. And it is hard to dispute that as Capitol Hill moves farther from the "public option," to...