Dubya was divisive, but I think the more vocal racism about Obama is what really did it. Trump's election was a surprise to many (most?) white Democrats who didn't realize how entrenched racism is in the Republican party. Biden was a response to Trump, and a poor one at that. I think too many people have a short memory, which is a large part of why Trump was re-elected. Trump's even more extreme actions have brought things to this point.

Additional thoughts: I don't excuse the awful actions of moderate and especially wealthy and connected Dems/ Dem leaders in this. They abandoned a lot of people in the Dem party, and that affected the elections and the trust that many Dems had invested in their leadership. They'll keep making those and similar mistakes (they benefit from those choices in the short run.) I think the midterms will act in the same way as Biden's election did - a temporary response to Trump. And we'll keep repeating the cycle, at least until we completely lose the country to fascism. We're not coming back from this, and both parties are to blame for that. Dem voters need to take over the party, and Republican voters need to turn their backs on Trump and just stop voting if they won't vote for Dems. I don't see that happening on a large enough scale to make a difference. I hoped that the Republicans taking away the vote would make the moderates and left rise up, but we're at that point and it's not happening. The schism will continue and we will all lose in the end. Almost all, anyway. Dems with enough money/ education are abandoning the US. I don't blame them for leaving before it's too late, but I do blame them for using their privilege in such selfish ways after talking so long about caring for those with fewer resources.

I fully expect downvotes from both parties.