Guests on "The Tonight Show with Jay Leno" usually appear to promote a movie, TV show, book or album, but President Obama will visit the NBC show Thursday to make the case for his financial rescue plans. While presidential candidates — as far back as Richard Nixon’s performance on “Rowan & Martin’s Laugh-In” in 1968 — have used comedy shows for campaigning, Obama becomes the first sitting president to appear. “We don’t look at it as the process of demonstrating the president’s sense of humor,” said White House spokesman Robert Gibbs
