I posted this in congressional elections thread a few weeks ago. I went back to review it, and I still think it all holds water.
The only thing I might add is that, in the month or two preceding the actual election, the Trump regime might dramatically soften their ground game when it comes to immigration, and also, do something dramatic to address consumer prices, maybe even send (or promise to send) a $1,000 check from the federal government in the names of their Republican congresspeople, or their Democratic congresspeople's Republican opponents, to sow doubt among independents and suppress their urgency to want to vote.