In this photo provided by NBC, Republican presidential candidate, former Massachusetts Gov. Mitt Romney talks with Jay Leno during his appearance on The Tonight Show in Burbank, Calif., Tuesday, March 27, 2012. Romney cracked Tuesday night that he'd pick Leno rival David Letterman as his vice president, talked at length about health policy and said he'd be happy to have a rival of his own, Rick Santorum, serve in a Romney administration. (AP Photo/NBC, Paul Drinkwater)