Trump is the real RINO.
For 166 years, the Republican Party has stood for the principles of our republican constitution and protecting such from threats both internal and domestic. He has insisted that everything, every principle, every value, every law be placed into secondary consideration to his erratic whims. This is not constitutionalism, this is not conservatism and sure is hell isn't Republicanism. This is arbitrary rule, plain and simple.
What we have is 25 true Republicans, and unknown split of cowards who are too afraid to admit either their Republicanism or their sycophantism and two avowed sycophants.
If Republicans across the board publicly voiced their concerns and criticisms with the aggression and passion of Trump, yes Trump would still have a powerful base but he would not have the influence he has today and the ability to dominate this party the way he has to this point. Just like with the mask issue, this is entirely the result of lack of voices from the top. If people were to challenge for the space, his influence would decline proportionally.
Right now this cowardice enables the small number of critics to be singled out as RINOs.