"Bad Day," the first single off Daniel Powter's small masterpiece of a debut disc, has been divebombing TV-watching Americans for months. Turn on "American Idol" and there it is, accompanying the latest axed contestant off the stage. Switch over to Showtime, and it's on promos for "Weeds." The VH1 video is inescapable. Yet nobody knows who the guy is (a 35-year-old French Canadian, it turns out), and attempts to compare him to other singers inevitably come up short. Powter is poppier than James Blunt, more substantial than Adam Levin, and way less hangdoggish than Train. He is--and there may be no flattering way of saying this--like the late-'70s pop king Leo Sayer: an elastic-voiced and enormously infectious singer who can make you feel like dancing in the space of a few deft keyboard plinks.