Here’s the thing. Trump’s hard core will stay loyal to him no matter what is said. They are like Perot’s supporter and like Ann Coulter (remember she said that she didn’t care if he did abortions in the West Wing?) Going after Trump is for the 65% of non-Trump supporters who are not sold on him. You need to show that he is not a real conservative. And that comes through relentless attacks and getting him flustered. We have already seen that, especially right after Iowa. Time to put on the brass knuckles and go to war if another candidate is to win, other than Trump. He has plenty of stuff to hit him on, but it needs to start in SC.
No, here's the thing: First, where the Hell are you getting "65%" of non-Trump supporters from? The supporters of Trump are completely in his suit pocket. They are not being swayed by public opinion polls, his past liberalism, or GOPe consultants, and they will not vote for any other Republican should the GOPe pull any shenanigans in Cleveland.
The other candidates in the race are simply fighting for VP or cabinet positions.