My country isn’t a two-party system, but I have often to vote for parties I hate to to prevent the extreme right from coming to power. Fuck I even did that a few weeks ago. If I were American I would vote for the Dems, but I would criticize them harshly, as I criticize harshly the parties I have to vote for here.
This is one of the things a Primary is for. It I’ll almost certainly vote Democrat in the general election, but well before that I’ll vote in the Democrat Prinary to raise my voice for a more liberal or Progressive candidate.
For Biden’s first term, I do believe the strong showing for more left wing candidates like AOC and the popularity of the “Green New Deal” influenced the platform for the better, even if those candidates weren’t chosen to represent the party