The dooming and "defeatist attitude" from some Dems gets kind of tiresome, imho. You would never hear a GOPer say stuff like that, even if their prez was at low 30s approvals. They always act and talk like winners and fighters, and that's what most people like.
Sure, things are not exactly going the way they should because (a) we lack a clear governing majority in congress to get stuff done while the GOP is unwilling to actually govern and (b) Biden is not a particularly charismatic politician, although he has his strengths such as personal engagement with voters and a ton of experience.
Just because Biden has medicore approvals at this point in time doesn't mean he - or any D candidate - is DOA in 2024. The previous presidents back to Clinton, and even some before, looked more vulnerable than they were in the end. The election won't take place for another 2.5 years, which is a lifetime in politics.
What Dems generally need to do, and what I'm kind of mad about, is get better in messaging, talk more kitchentable issues and call out Republican extremism more forcefully. And with that I mean how their agenda would hurt average Joe types, not just repeat the "orange man bad" stuff. Leave Trump alone with his legal problems and revelations; there's a reason he was voted out of office; simply because many Americans were tired of him.
Pretty much this.
Also, even if the Democrats at some point lose to a Republican trifecta, there's always some kind of reckoning after that happened. Neither party is likely to hold a permanent majority in the near future. It's also not the case that the Republican agenda is pretty popular across the board.
Democrats need to run much more on accomplishments and not talk everything down, even if they suffer a political loss or a vote in congress. Unfortunately this isn't a uniquely American thing, some other center-left parties do the same. Of course liberals and Social Democrats tend to have more reform ambitions that are much harder to achieve.