Trump seems to have a stronghold on his party that no candidate can shake. As Barbara Perry, director of presidential studies at the University of Virginia's Miller Center put it, Trump has simply proven, time and time again, "that all previous rules do not apply." "When we look back at the lessons of history, they may repeat themselves, but they haven't so far," Perry said. "He may get a challenge by either a strong gadfly or a strong personality or a strong presence in the party," just as Ronald Reagan was to Ford in 1976 and Ted Kennedy was to Carter in 1980. "But I don't see that person on the horizon."