On Reagan 1976 I'll recycle something I posted here some time back:
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You have to remember that the choice of Schweiker was a desperation move, at a time when Ford was ahead in delegates--indeed, he was very close to being over the top. (Hence, the unusual conduct of a non-incumbent announcing his running mate in advance.) Really, it was between Schweiker and Governor James Rhodes of Ohio:
"Previously, Sears had reviewed the situation with Laxalt after talking it over with Black and Keene. All parties agreed that something needed to be done, but the pickings in the GOP were pretty slim. Choices for a running mate came down to Governor Jim Rhodes of Ohio and Schweiker--although some conservatives felt a case could have been made for Senator James Buckley of New York.
"Rhodes controlled the ninety-seven Ohio delegates and most likely could have delivered them while not antagonizing Reagan's conservative delegates. All parties agreed that if winning the convention were the only goal, Rhodes would have made sense. But no one wanted to run a general election with the curmudgeonly and controversial Rhodes. Jules Witcover described him as 'slightly unsavory' in *Marathon* and Sears dryly told Witcover his feeling about the choice of Rhodes: 'You've got to have some responsibility in this business.'"
https://books.google.com/books?id=fPWPDH-0TZYC&pg=PA272
One should remember that Schweiker was not all *that* liberal, especially on non-economic issues (and on economic issues he was after all from a heavily unionized state)--in particular, he was pro-gun and anti-abortion. It was therefore plausible to think that he would not alienate conservatives too much. And Sears definitely thought Reagan had to reach out to moderates to win both the nomination and the election. He had tried to get William Ruckelshaus (a Catholic and a moderate from Indiana--and of course, along with Elilot Richardson, the man who had refused to fire Archibald Cox...) on the ticket--but Reagan already controlled the Indiana delegation, at least on the first ballot.
But Sears' real first choice is shocking--Nelson Rockefeller! When asked what the reaction of Helms and other conservatives would be, Sears replied "They would have come off the ceiling in a day or two." Sears added, "I thought very strongly that he [Rockefeller] would have liked the irony of it, and he had firm control of his delegates. And, Mrs. Reagan liked him a lot. But you couldn't trust that others wouldn't talk him out of it, and you couldn't take that chance."
"Although Rockefeller controlled Dick Rosenbaum and Rosenbaum controlled the vast majority of the New York delegation, it is unknown whether delegates would have gone along with them and supported Reagan had Rockefeller joined the ticket. Still, it was no secret that Rockefeller and Rosenbaum were angry and dismayed over the treatment afforded Rockefeller by Ford and the President Ford Committee. The question is whether Reagan could hold his conservative delegates in the face of such a selection..."
https://books.google.com/books?id=fPWPDH-0TZYC&pg=PA273