This is what I mean though, they're putting their own interest and egos over the interest of the nation, which should be to prevent Trump winning again and, if possible, put in place a moderate democratic president who can win another 2 terms.
Bringing in a credible figure from outside of politics who has good standing would massively dent Trump's ability to play into the populist anti-political class feeling in the US.
He's net favourable because he's a benign old man who is very good at articulating populist positions but has barely any power or influence over anybody or anything. He's the US version of Tony Benn - loveable for his principled stance on some issues but would never withstand the scrutiny of an election. Trump would wipe the floor with him.
Would you take a step to advance your politics that would leave you beholden to upper management forever, and grant them the absolute ability to terminate your employment without cause or legal recourse at their discretion? I doubt it. Don't ask politicians to act that selflessly, then. It's not realistic.
As for Bernie, the ground shifted. He would have had a bad time in 2020 over his Israel position. His longstanding anti-China position came up smelling like roses, sentiment is broadly anti-corporate, and his populist approach to health care looks better with every passing year. People
with insurance can't even get essential medications in this country, because the FDA and Congress are hopelessly incapable of ensuring those licensed to produce medications can maintain adequate supply. Insurers treat multi-billion-dollar fines as a cost of doing business, because they know they're bilking Medicare out of more.
I might not agree with all of Bernie's positions on healthcare, but it's clear radical change is needed.