The fat lady is about to sing for Newt Gingrich. So says the former speaker's biggest backer, Sheldon Adelson. Speaking to a crowd in Las Vegas, Adelson said that mathematically Gingrich can't be the nominee—and that a brokered convention is becoming increasingly unlikely. Gingrich is "at the end of his line," said Adelson, as reported by JewishJournal.com. Adelson and his family have donated $16.5 million to Gingrich's Super PAC, Winning Our Future, which has taken in a total of $18.8 million so far. Adelson took a swipe at the remaining candidates, saying Mitt Romney isn't a good leader and Rick Santorum is too focused on social issues.