Jurisdictions are becoming ever more partisan. So now only the most partisan (divisive) candidates can win their primary election, which then pretty much makes the general election moot.
The fix is California style redistricting, where citizens and not politicians are in charge of the process.
I think that there is almost precisely zero evidence of this; there's a lot more to support that regional strong political divides have always been present in the US, what's new is that the salient issues have become increasingly consistent nationally, so that it is no more the case that the national political scene often seems less sharply divided because all the sharp regional divides used to be in different places, whereas now there are more common national divides.
> The fix is California style redistricting, where citizens and not politicians are in charge of the process.
Non/bipartisan redistricting by notionally independent commissions (which, often, as in California, legislators actually have a role in choosing members for, so they aren't truly independent of the legislators, though they are certainly less accountable than legislators) has been a growing trend in the same time as the increasing polarization in national politics. So, its pretty clearly not fixing the problem.
It becomes a "Team up? What for?" situation