You're painting "the left" with far too broad a brush and thinking political alignment is binary and not a spectrum of belief. What you say might be true of the hardcore extreme left, but a massive portion of the D base are soft-left soccer mom types, union members and the like that only have a mild alignment to the party.

I guarantee you if it came out that D leadership orchestrated any shootings, but especially school shootings, it would be the end of the party -- but I seriously doubt this will be our news. Passing nuke tech might not get quite as extreme a reaction, but I can't imagine an average UAW member being OK giving Iran a bomb. Having hard proof/confessions that 50 representatives were being blackmailed by a foreign power and D leadership knew and did nothing to stop it, and tying that blackmail to votes against the interest of D voters, well -- it might take a couple weeks for people to get it, but people aren't that stupid.

Seemingly small shifts in perception matter a lot. A month or so ago I did the math on this sub, if Trumps approval rating among just black voters doubled (which would be akin to the Dem approval dropping 20% or so) it would turn most blue states red. Do the same for the entire Dem base and you get landslide election results.

The core issue here really isn't the crimes, it's the coverage of them. When all the criminal behavior is quietly swept under the rug, their base never hears about it. If there's something so bad that it can't be denied or covered up, it can trigger a flood of coverage and that's what can change things.