I’ll answer the questions a bit out of order here.
First, I don’t think it’s accurate to say DeSantis and Trump are similar ideologically. Certainly there is some overlap there. But I don’t even think it’s accurate to say that Trump HAS an ideology. Trump will say whatever it takes to get attention. Populism is a tactic more than an ideology, and Trump is a populist first and foremost, but I don’t think he REALLY gives a flying F about the ideologies. He’s anti-immigration because it’s convenenient. Because Pat Buchanon and others had already created a large anti-immigrant movement within the GOP for him to exploit. If it were hating the number Six, Trump would be a Six-Hater.
By contrast, yes, DeSantis is an immigration hawk…but much less so than Trump. Yes, he’s a populist, but one who I think actually has his own views and ideas that ground him. Agree or disagree with them, I don’t think Trump ever really had that. Trump adopted some stereotypical conservative positions after being on the opposite side prior to his 2016 campaign. For example, Republicans seem to forget that Trump was pro-gun control…until 2016. He’s tailoring his ‘ideas’ to what he thinks will get him the results he wants.
Second, I don’t think Democrats want DeSantis. They want the GOP to nominate Trump some more. It’s good for TV ratings and website clicks for one thing. But also, Trump is REALLY bad for the GOP. He might even be worse than (for example) Bernie would have been for the Democrats. Trump ‘won’ in 2016, but lost by proxy in 2018 and 2022, and lost himself in 2020. Even his ‘win’ has to be in sarcasti-quotes because he beat a terrible candidate who ran a terrible campaign and he STILL needed the 7–10 split of politics to do it – namely winning the electoral college without winning the popular vote. Which is rare and hard to do and signals a weak win.
Democrats spent the last three election cycles DESPERATELY trying to tie Trump to every downballot Republican. Voters have generally been splitting their tickets the last few elections, which is historically rare. They vote against Trump and Trumpy-Republicans, and FOR non-Trumpy Republicans. The GOP is making inroads for the first time in decades with blacks and hispanics….and yet, Trump-endorsed candidates lose in all but the safest races. Being endorsed by Trump is the kiss of death unless you’re in a heavy red district. So they WANT him to be nominated because they’re confident that they can run LITERALLY ANYONE against him and win. If Trump looks like he’s sailing to a nomination, expect the Democrats to nominate a more radical candidate because they’ll feel more confident that they can win the general.
Third – who get nominated? That’s SO hard to say this early. I’m not even 100% sure that DeSantis is the main challenger to Trump, though it sure looks like it right now. I think Trump’s base is SO passionate for him and has constructed this little echo chamber where they just disbelieve all the negative that if I had to bet the mortgage, I’d probably put it on Trump. But it’s a tough call. DeSantis has something Trump doesn’t – competence. A track record of success. But Trump’s core clearly doesn’t care about that kind of stuff or they wouldn’t have voted for him in the first place.
I think there’s a very substantial chunk of the GOP that doesn’t want Trump. A majority in fact. But I don’t know if they’re the kind of voters that show up for primaries. Primary voters tend to be the most partisan and the most energetic. That’s part of why primaries are a bad construct for narrowing down candidates and I’d like to see them replaced with an instant runoff system like Ranked Choice or Multivote instead. And I think that plays into Trump’s strength. Say what you like about them otherwise, but Trump inspires PASSION…both for and against him.
So ultimately, I think I’d give an edge to Trump winning the nomination.
Here’s the other thing you didn’t ask though—If Trump loses:
1) Will he accept the loss or claim fraud?
2) Will he mount a third party campaign to split the GOP vote as an act of revenge?
I think the answers are Yes and Yes.