Frank Knox, FDR’s Secretary of the Navy, was the GOP candidate for vice president in 1936. Today, he would be called a RINO.
Maybe, but what would you do if you were in Knox’s shoes? He was a major opponent of FDR, but Roosevelt needed the appearance of bipartisanship when it came to defense policy. Someone needed to build the two-ocean Navy, and national security trumps politics at some point.
Wendell Willkie ran as a Democrat in 1932, losing the nomination to FDR, then switched parties (finally) in 1939, and ran against FDR as a Republican. Somewhere around here is an original copy of "One World by Wendell Willkie" with his thanks to FDR for letting the publisher use the paper to print it. Naturally, the leftist partisan media shills pretend to be impressed by Willkie and do their tired old woe-is-me act that his alleged vision didn't win out.