MS NOW

How Donald Trump could shut down an open convention

Donald Trump may have an ace in the hole with Pennsylvania's unbound delegates that could lift him past that magic delegate number.

Republican presidential candidate Donald Trump speaks during a campaign event at an airplane hanger in Rochester, New York, April 10, 2016. (Photo by Carlo Allegri/Reuters)
Republican presidential candidate Donald Trump speaks during a campaign event at an airplane hanger in Rochester, New York, April 10, 2016.REUTERS

Steve Kornacki

Steve Kornacki, author of "The Red and the Blue: 1990s and the Birth of Political Tribalism," is a national political correspondent for NBC News and MSNBC.