For the first time since October 1999, McCain's favorability rating among American voters has dropped below 50 percent. A Gallup poll taken last month showed him at 48 percent, down 6 points from November, and down from a high of 67 percent in February 2000. Giuliani, in contrast, has held above 60 percent favorability in Gallup polls, most recently at 62 percent. Now that Giuliani has signaled a serious intention to run, stating on Monday "I'm in this to win" as he filed papers with the Federal Election Commission, the comparisons grow in importance. For Giuliani, winning over enough of...