Allan Lichtman said that Trump's victory was inevitable, based on the premise that elections are "primarily a reflection on the performance of the party in power." Lichtman, an American political historian and professor of history who teaches at American University, has predicted the correct outcome of every presidential election since 1984 (except for 2000, when he picked Al Gore, who won the popular vote). His book, Predicting the Next President: The Keys to the White House 2016, uses a historically based system of keys to predict election results ahead of time.