Primaries
1964: Barry Goldwater
1968: George Romney
1972: John Ashbrook
1976: Ronald Reagan
1980: Ronald Reagan
1984: Ronald Reagan
1988: George Bush
1992: George Bush
1996: Kemp or Buchanan
2000: George W. Bush
2004: George W. Bush
2008: Mitt Romney
People appear to think George Romney was a conservative like the post-Massachusetts version of Mitt Romney. In reality, George Romney was the moderate-to-liberal candidate in the 1968 Republican parties (and would probably be considered a liberal in today's political environment). He ran against the Viet Nam War and in 1964 refused to endorse Barry Goldwater in the general. It would've been strange for a Goldwater/Ashbrook/Reagan Republican to vote for Romney in 1968, particularly considering there was a conservative running, Ronald Reagan himself.