Murtha's Okinawa answer embarrassed Democratic House members who would not dream of criticizing publicly the former back-room pol who became an icon to the party's antiwar base last November by calling for an immediate troop withdrawal. His performance on ''Meet the Press'' reinforced dismay inside the party that Murtha, at age 74, has announced his candidacy for majority leader if the Democrats regain control of the House. Murtha proves there are second acts in American politics. I had forgotten that federal prosecutors designated him an unindicted co-conspirator in the Abscam investigation 26 years ago. I was reminded of it after...