The home stretch of the long 2016 GOP presidential race is coming into view, and the path to victory is opening wider for front-runner Donald Trump amid signs that he could pick up a big win in Tuesday’s Indiana primary.

A new Wall Street Journal/NBC News/Marist poll finds Mr. Trump ahead by 15 points among likely Republican primary voters in Indiana, pointing to a victory that would significantly boost the businessman’s chances of clinching the Republican presidential nomination before the party’s convention in Cleveland.

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