Kyrsten Sinema has been a thorn in the side of Democrats for the last two years. Unlike, co-thorn Joe Manchin, there’s no obvious reason why she insisted on being one. (As Eric Levitz notes, Mark Kelly’s victory is an indictment of Sinema’s politics.) Manchin is from the most pro-Trump state in the country. Sinema’s not.

In recent weeks, Rep. Ruben Gallego has been signaling more and more clearly that he may challenge Sinema in a primary in advance of her reelection campaign in 2024. Normally in such circumstances partisans try to find a balance between disciplining or displacing an errant elected official and the risk of losing the seat altogether. But that mistakes the challenge Democrats actually face. Because Sinema is already unelectable.

Let’s start with the fact that 2024 is going to be a very challenging year for the Democrats to hold the Senate. The pick-up opportunities are challenging at best. Democrats must defend seats in Ohio, Montana and West Virginia. In other words, Democrats can’t afford to lose a seat in Arizona if they have hopes of retaining Senate control.

I watched Donald Trump’s special announcement speech last night. I don’t think it was quite as low energy as some have suggested. I’d describe it more as a greatest hits show from an old band. Some have noted that the crowd seemed not always to know when to clap. They were into it but not overwhelmed. This raised a question in my mind. This is not really Trump’s crowd. Trump’s crowd is at those red state rallies. He did himself a disservice by not holding the event at one of those venues. It’s possible that his handlers thought this was a venue where they could keep him more on script. More likely, he’s reacting in a panicked fashion to the DeSantis boomlet and didn’t have the time.

But let’s set the atmospherics aside. I think this is likely the beginning of the end of Donald Trump. But I say this with a different emphasis from most. When I say “beginning of the end” I put the emphasis on “beginning.” There can be a long time between the beginning of the end and the end of the end. I suspect in this case it may play out over a few political cycles.