Patterson, Thomas E. "Pre-Primary News Coverage of the 2016 Presidential Race: Trump’s Rise, Sanders’ Emergence, Clinton’s Struggle." HKS Faculty Research Working Paper Series RWP16-023, June 2016.
What’s the best predictor of which candidate will win the presidential nomination? The winner of the Iowa caucus? The winner of the New Hampshire primary? Actually neither is as good an indicator as the winner of what political scientists call “the invisible primary”—the period before a single primary or caucus vote is cast. A fast start in Iowa or New Hampshire is important. A candidate with a poor showing in both states is in trouble. Voters aren’t interested, donors aren’t interested, and reporters aren’t interested in a candidate who finishes at the back of the pack. Yet, more often than not, the winner in Iowa has lost in New Hampshire. Since 1980, of the twelve open nominating races—those without an incumbent president seeking reelection—only Al Gore in 2000 and John Kerry in 2004 won both contests. In 1992, the eventual Democratic nominee, Bill Clinton, lost both, though he ran well enough in the two states to be seen as a viable candidate.