Which makes the looming choice a genuinely fraught one for the future of the party. Rubio aspires to be Reagan (with a dash of Bill Clinton-in-1992 thrown in) but risks being another Dubya. Cruz aspires to be Reagan (with a dash of the elder Bush and Richard Nixon) but might be Barry Goldwater in 1964. And then Trump aspires to be no one but himself, a mash-up of Ross Perot, Pat Buchanan, Silvio Berlusconi — and Jean-Marie Le Pen.

So a vote for Rubio is a vote for adaptation and ambition — for a conservatism that seeks to reassure the anxious middle on domestic policy and shore up the Pax Americana overseas. A vote for Cruz is a vote for rigor and retrenchment — for a more intensely ideological conservatism at home and a narrower definition of the national interest abroad. A vote for Trump is a vote for rupture — for a conservatism defined more by identity politics than ideology, more by nationalism than libertarianism, more by caudillism than the Constitution.

I have sympathy for all three of these tendencies — if not necessarily the men who currently embody them — and I think the ideal nominee would find a way to synthesize them, to sift the best and the worst of each.