I run a Senate Forecast at RacetotheWH, and Democrats’ chances of holding on to the majority just rose to their highest level, 51.5%, since the New Jersey and Virginia elections last November. It looks like Republicans might get another bad break in the primaries, this time at the hands of Donald Trump. He's doing a fundraiser with Arizona Senate candidate Blake Masters.
My forecast is not impressed by Masters candidacy in the general election, and it thinks he would only have a 31% chance of beating Mark Kelly. Master is polling 10% behind Kelly and has never run for office before. Now that Trump is doing an even with Masters, I imagine it's more likely than not Masters win Trump's endorsement, so I increased the odds that he is the nominee.
Masters would be a huge drop-off for the GOP compared to the current primary front-runner, Attorney General Brnovich. Brnovich has already shown he can win tough elections, winning a second term in 2018. The forecast thinks he would have a 52% chance of beating Kelly.
Republicans chance of winning Arizona shrinks to 31% if Blake Masters is the nominee. AZ Forecast
This is becoming a real problem for Republicans. Trump is supporting weak candidates like Herschel Walker, and perhaps deterring stronger ones from even running (GA, NH & PA come to mind). It's a difference in strategic goals among party leaders. Mitch McConnell wants to win back the Senate majority. Trump would prefer Republicans in charge, but his primary objective is to elevate loyalists and control the party, especially the Senate. I suspect the blatant refusal of over 80% of GOP Senators to support his attempts to overturn the electoral college looms large here.
The problem for the GOP is that Trump loyalists, especially those that are first-time politicians, are not the strongest candidates. If the GOP narrowly loses the Senate, he's going to be a big part of the reason why.
For the full Senate Forecast — which was more accurate at predicting the final margin in the Senate than Nate Silver’s 538 last year — click here. You can also check out how the different potential GOP nominees poll and perform in the forecast against Mark Kelly in our AZ interactive forecast.