I am glad you remembered that. Indeed Reagan was not only a democrat but also involved in labor union activities.
As smart as I am, even I was a democrat until 1968. But I saw the light and became a republican pretty early.
You aren’t so smart, and even you switched from the democrats, as Reagan was sitting in California as a Republican governor in the 1960s.
That isn’t Trump’s story, he was a democrat in 2009, under Obama, and he had at one time been a republican.