I suppose it should come as no surprise to anyone the adage "Leopards don't change their spots" has nothing to do with politics. However, in the case of Ronald Reagan, it would seem (at least in the eyes of his fervent supporters and those entrusted with re-writing history) he was never anything but the personification of Conservatism and hardline Right Wing ideology.
Well, no. There was that blip in the radar during the FDR and Truman years where Ronald Reagan was a big New Deal supporter as is evidenced by this campaign address on behalf of Truman's re-election bid in 1948 as well as the election of then-Mayor Hubert Humphrey to the Senate in Minnesota.
Ronald Reagan: “The profits of corporations have doubled, while workers wages have only increased by one quarter. In other words, profits have gone up four times as much as wages. And the small increase the workers did receive was more than eaten up by rising prices which have also bored into their savings. For example, here’s an Associated Press dispatch I read the other day about Smith L. Carpenter, a carpenter in Union Springs New York. Seems that Mister Carpenter retired some years ago thinking he had enough money saved so that he could live out his last years without having to worry. But he didn’t figure on this Republican inflation which ate up all his savings. And so he’s gone back to work. The reason this is news; is Mister Carpenter is ninety-one years old. Now take as a contrast the Standard Oil Company of New Jersey which reported a net profit of two hundred and ten million dollars, after taxes, for the first half of 1948. An increase of 70% in one year.”
The rest, as they say, is history.