Apart from the true brainwashed believers, who are quite loud and obnoxious, I think most Republicans would privately admit to you that they know he's ridiculous. I really don't think 74 million Americans are that dense.
Amid all the din and fury and social media rage, as usual with Republicans, I believe it boils down to not what he stands for, but what he stands against. And those things would be, in no particular order:
--Public health
--Minority rights
--LGBTQ progress
--Women's reproductive rights
--Immigration
--Secularism
--Commonsense gun control
--A fair tax code
--Corporate accountability
--Environmental protections
--Diplomacy
--The notion of public responsibility for anything
--The notion of an accountable and functioning government
--Ultimately, democracy itself, because they realize there isn't a majority in this country committed to stopping these things, so rigging the system and entrenching rural-based minority rule is the only way.
Most Republicans appear to have concluded he's the best or only battering ram they have, and they're willing to make a deal with the devil and support Trump despite his glaring flaws and hypocrisies.
Honestly I don't know who's worse: The brainwashed Trumpist true believers or the cold and calculating mini-McConnells of the world who ally with Trump out of self-interest because they are just fundamentally anti-social and opposed to progress.