Both came out of the popular culture, Reagan out of Hollywood, Trump out of a successful reality TV show. Both possessed the gifts of showmen — extraordinarily valuable political assets in a television age that deals cruelly with the uncharismatic.

Both became instruments of insurgencies out to overthrow the establishment of the party whose nomination they were seeking.

Reagan emerged as the champion of the postwar conservatism that had captured the Republican Party with Barry Goldwater's nomination in 1964. His victory in 1980 came at the apogee of conservative power.

The populism that enabled Trump to crush 16 Republican rivals and put him over the top in Pennsylvania, Wisconsin and Michigan had also arisen a decade and a half before — in the 1990s.A decisive advantage Reagan and Trump both enjoyed is that in their decisive years, the establishments of both parties were seen as having failed the nation.