Billionaire Sheldon Adelson, by far the biggest financial backer of Newt Gingrich's presidential bid, is preparing to open his wallet again. But this time, the casino magnate appears to have more than one agenda. In a bit of political chess, Mr. Adelson is ready to not only directly support the former House speaker in the Republican primary, but to use his cash to push Rick Santorum from his position atop the latest national polls, according to people to have discussed the matter with Mr. Adelson. Enlarge Image ADELSON ADELSON Las Vegas Review-Journal/Associated Press Sheldon Adelson, shown with his wife, Miriam,...