If I recall from my history class, the political parties did a very strange swap. I recall that the Democratic party was actually the Conservative Party (what we now know as Republicans) — the current Republic party became born of the Whig party during Lincoln’s era, who believed in very liberal government involvement with the economy.
While trying to verify this, I actually found this post, which is a pretty fascinating take on how our political parties shifted in the last 100 years: https://www.quora.com/Is-it-true-that-Democrats-used-to-be-the-conservative-party-and-Republicans-used-to-be-the-progressive-party
According to this, Roosevelt actually seems to have started the swing toward the Republican party being as it is today. Meanwhile, it seems that it took until Civil Rights for the Democratic party to morph into what it is today. Note, too, that the professor making the comment indicates that there’s certain platforms in yesterday’s Democrat party that today’s Republican party has adopted — namely, things like lower taxes, less government involvement, etc. This is a paradigm shift from what the parties originally represented.
Super interesting stuff — that even though they bear the same names, at least in that era, they had begun a shift into where they are now. It would be more accurate to actually reverse which parties voted for what. That said, both parties tended to be relatively classist, misogynist, and racist in terms of policy.