Bernie
He had been an independent. He had stood against the duopoly. He said he wanted to open up the system. He wanted to move the country toward the kind of social democracy prevalent in Europe.
Then he started to work with the Democrats. They said to him: “Socialism is not popular in this country; either join the team and drop the socialism stuff or remain at the margins.” The Terribility of Trump gave Bernie an excuse to say that the most important thing now is to promote the progressive bloc … as (relatively speaking) represented by the Democratic Party.
He has lots of support for that sentiment. He dropped the radicalism and was neutered.