This question reminds me of when Pres. Reagan switched to the Republican party, which was around the same time my parents did, and for the same reason, they didn’t leave the Dem party, the dems left them.
The last time Reagan voted democrat for president was in 1948.
By 1952 Reagan was campaigning for Republicans as a “Democrat for Eisenhower”, he kept using that anti-liberal, conservative club until 1962.
In 1952 Reagan was campaigning for Republicans like Eisenhower who he campaigned for again in 1956, and then campaigned for Nixon against JFK in 1960, already having earned a reputation as an active speaker for conservatism for years.
Reagan formally registered Republican in 1962 and made a famous speech at the Goldwater convention in 1964.
I loved Ronald Reagan, and was his biggest fan, but I never bought into that line of his. The Dems in the 1930s were a combination of socialist and national socialist. One faction admired the Soviets, another the Nazis. Their policies emulated both in many respects, and they would have gone farther if they could. Reagan was a Dem in the 1930s. They didn’t leave him; he got educated. His experience in the 40s fighting communists in the unions was part of that. The biggest part was his tutelage under the President of GE in the 50s. Dems were actually less socialist in the 50s than in the 30s. They had gotten rid of their fringe element for the most part by then. (The fringe came back, though, in the 60s.)