Republicans were very aggressive at brainwashing their base and turning them into toxic idiots. They created "news" outlets (while making the legit news sources verboten) and YouTube channels and all this other shit. They wound their politics tight around religion because they knew their base is already highly manipulated by religion, and every good cult leader -- Manson, Koresh, Jim Jones, you name it -- always starts with Christianity and then slowly fits themselves into the Jesus role, because it's easier to swap around something that's already been built, rather than start from the ground up. They figured out what a bunch of mean-spirited, unhappy messes they had on their hands for voters, and they appealed to all the worst in them -- racism, selfishness, sexism, stupidity, fear, and built everything they've got on culture wars and an addiction to rage. Trump appealed to all of that, because he's an idiot, and he's an asshole... just like them. He tells them it's okay to be those things.
And Trump just makes one bad decision on top of another... enough so that it starts to embarrass the rest of the Republican party. Honestly, they don't care if they're buddy-buddy with Nazis, they just care if the public sees that. Trump's not careful enough about not inviting Nazis to Thanksgiving and it creates a P.R. problem.
They don't really care if Trump owes money to enemy dictators and is manipulated by them -- https://www.yahoo.com/news/trump-had-hidden-19-8-125434457.html -- that's par for the course with Republicans. They just don't like that he didn't bury it deep enough and it makes them look bad. They hate having to defend it, even if they don't care about it.
They don't care if Trump wants to throw out the Constitution... so do they! But that's not the message they want to send. The whole trick is to gut the Constitution while they say they're championing it. They know their base will listen to what they're told rather than watch what they're actually doing, because they've cultivated that base until they're basically children, with a child's ability to understand facts. They know their base is so stupid and tribal-bent that they even run candidates like Hershel Walker. Hey, Marjorie Taylor Greene's popular, why not just run somebody with the brain of a brick? The base knows more about vampires and werewolves than it does policy, anyway.
Now that they have another creep they want to push, who they think will have slightly better impulse control, they want to dump Trump to the wayside. Rest assured, when they claim they have a "deep field" all they're talking about is DeSantis, because I know that peesquirt Marco Rubio, that phlegmwad Ted Cruz, and all the other pathetically-hopefuls (there's nothing sadder than watching Nikki Haley try so hard for a position nobody's even going to consider her for) don't have a hope in Hell. The Republican base likes bullies, and Rubio and Cruz and the rest are toadies. They're the bully's sidekick. DeSantis is the only one who seems like he could be a bully on his own... but he's reportedly really uncomfortable with confrontation, even though he snaps at people a lot, so he may not be up to it.
And the base that they built still wants Trump. When the Republican party sees they went too far and wants to dial back the level of stupid in their base... they can't. And it's embarrassing them.
Trump's going to keep saying things like "throw out the Constitution" because he knows his base won't punish him for it. They're so far gone they'll defend everything, just as long as "the libs" hate it. The Republican voter base has no real principles anymore and they're ready to throw their all into jousting imaginary windmills (CRT! "wokeism"!) while their leaders steal everything from them, including their country and including their rights.