Ex-president Bill Clinton sounded confident on Monday when he told a Philadelphia crowd that John Kerry would win the White House and "make America the comeback country." But yesterday in Florida, the recuperating heart patient sounded a little less certain. "I think it is slightly more likely that he will win, but this thing is tight as a tick," Clinton told the Magazine Publishers of American gathering in Boca Raton. One reason for the uncertainty: Dubya enjoys "negative campaigning" in a way his father, who Clinton defeated 12 years ago, never did. "It was a pretty negative campaign, but I...