Both parties have failed to act, but now that one party has finally caught up to reality in this one area, only one party is actively obstructing something that is an obvious necessity.
Last I checked, the Democrats are in charge of virtually all of the cities where this is happening, as well as most of the states. No reason this can't get done at the state and local levels.
If QI was a law, the supremacy clause would certainly apply.
But QI is not a law, however it is a policy created by the courts based on federal law. It’s not clear to me whether the supremacy clause applies here, but I suspect it does.
Just like card check. You'll get tax rebates on medical procedures following officer involved incidents if your lucky.
Same with the Republican Party. So I have no idea which party you are referring to that has "caught up with reality". Certainly there's a segment of mostly-Democratic voters who oppose QI, but... they aren't represented among leadership at all.
I would personally count that as leadership not supporting QI.