How Trump can lock up GOP nomination before the convention

FILE - In this April 15, 2016 file photo, Republican presidential candidate Donald Trump speaks in Hartford, Conn. To all the political junkies yearning for a contested Republican convention this summer: Not so fast. It’s still possible for Donald Trump to clinch the nomination by the end of the primaries on June 7. His path is narrow and fraught with peril. But it’s plausible and starts with a big win on Tuesday in his home state New York primary. (AP Photo/Charles Krupa, File)