In 1964, frustrated and angry Republicans nominated Barry Goldwater, a very conservative U.S. senator from Arizona. But he was unelectable nationally, and incumbent President Lyndon Baines Johnson won in a landslide. The GOP establishment vowed never to make that mistake again.

Since that historic defeat, Republicans have nominated not the most conservative candidate but the candidate who was at least conservative enough and also electable. This was true for the elections of Richard Nixon and Ronald Reagan. In 1988, Pat Robertson was the most conservative candidate, but he was unelectable nationally; conservative-yet-electable George H.W. Bush became the nominee. That pattern held in 1996, 2000, 2008, and 2012.

Today, however, many angry and frustrated Republicans are veering from this model–and supporting the candidate who is many ways is not only the least conservative of the 2016 field but also the most unelectable.