There would have to be a party of inspiring politicians that can inspire some confidence that something will positively change. People vote for change.

Obama ran on the idea that the old guard, the old government, had to be changed and he would bring in a completely different government.

So did Trump.

So did Bush.

So did Clinton.

So did The Other Bush...

And so on. The only thing that engages voters is blatant admission that the US government is horrifically formed, inefficient, and objectively is not a representative democracy by any possible definition of those words separately or together; and the promise they will fight to make it more of a representative democracy.

When Kamala Harris came out and said 'oh the Biden administration has made everything so much better so we're going to just do more of the same' when every single demographic under a 400k net worth was objectively worse off under Biden than they were under Trump (yes, yes, extenuating circumstances, blah blah recovering from a global pandemic Trump would have made worse) people could not get behind that message.

When Harris promised to stay the course, her campaign ended. When Biden promised to keep doing what he was doing, his campaign ended. It wouldn't have mattered if the bastard child of the literal incarnation of the Evangelical Christian Devil and Hitler transformed into an eldritch cosmic being that turned every person that gazed into it into a statue ran as the republican candidate, it would have won against the Harris campaign.

At the very least any candidate that wants to win has to acknowledge how incredibly awful the modern American has it. We have worse wealth inequality in the US than at any point in WORLD history. Slaves in the American South had less wealth inequality towards the richest kings of Europe than we comparatively have towards the owners of the US.

Any Candidate then has to, at the very least, pay lip service to the idea that drastic, severe, violent change needs to happen. There is no more incrementalism. There is no more 'lesser evil.' There is no more 'we sacrifice our generation so the next can maybe have it better but we're not going to do anything to realise that anytime soon.' We are a full fucking century past that idea. We are a century deep into that idea. It has not worked. It will not work.

tl;dr Promise change, don't have a history of promising change and then doing nothing, don't shy away from violent rhetoric, don't 'play politics' and be nice to the ruling class, don't pretend incrementalism or lesser evilism works when we have a century of proof that it doesn't.

Modern Dems are right of Reagan.