(Reuters) Front-runner Donald Trump said on Sunday that he will have essentially sealed the Republican U.S. presidential nomination if he wins Tuesday’s contest in Indiana, where he holds a big lead over chief rival Ted Cruz. A new NBC/Wall Street Journal/Marist opinion poll showed Trump with a wide lead in Indiana, 49 percent to 34 percent for Cruz and 13 percent for a third candidate, Ohio Governor John Kasich. Trump, a 69-year-old billionaire real […]