The reality is that the main reason for the attacks on Donald J Trump by republicans is that he is viewed as a threat to the "party" as they will not be able to control him.  He really does not represent the republican party as it stands now. Hopefully the party will realize they have to change.
 With that said the republican party as it stands now (and for many years) does not represent conservative republicans, it represents the republican party and it's self interest. Having been a party member for 40 years I have finally switched to undeclared as I could no longer support a party that does not represent my values.
 Why? After personal experience with our local/state legislature and how the political system really works I have lost all faith in the party (politicians).