Now that John McCain has taken care of his political business in Arizona, it is time for him to return to Washington and the responsibilities he bears as a leader of the Republican Party and the nation. (snip) One of the conspicuous failings in the past few years has been the absence of a second party making principled decisions on when to support and when to oppose the president. McCain has the best opportunity -- and the best credentials -- to restore this. (snip) It is up to McCain to choose when and how to exert the influence he commands......