I think there's still important differences economically even when considering them both to be center right. There's a strong push for higher taxes on the wealthy and a higher minimum wage among Democrats -- the only reason we didn't see a minimum wage increase is because 1 Democrat opposed it vs the 49 other senators. And while our system still needs work, it doesn't mean there haven't been significant changes.

There's a brilliant provision in the Inflation Reduction Act for instance that ends the corporate tax loophole for the largest corporations. A company above a certain size that makes very high revenue (>1 bil iirc) is required to pay at least 20% in taxes. They can't loophole their way to $0. The big corporations are going to have to pay actual taxes now.

I'm not going to pretend that Democrats are perfect, but I do think there's a messaging problem and a tendency to let good works speak for themselves -- which doesn't work. If you remember the rail worker strike that Congress and Biden stopped, that actually wasn't the end of it. Union leaders have said that the administration continued to work behind the scenes with the unions to pressure the rail companies, and because of that, they've gotten the sick days they were demanding.

I would need to do a lot of research to say more about if leftism ever had a serious shake in the US or not, I'll admit. My assumption is that it was rejected, given the progressivism of the New Deal era didn't persist. But I do need to do more reading.