The problem is that Trump is unlike any other republican they could possibly face. Romney was embarrassed by his wealth, Trump isn’t. Everyone already knows that Trump is wealthy, so any attack along that line will fail. Trump has been around for decades, so any illegal business dealings or poor treatment of employees would have been exposed years ago if there was anything there. So, I don’t know what line of attack they could follow.
Trump has numerous lines of attack against Hillary, and I’m sure he’ll exploit every one of them, and won’t be afraid to do so.
Trump is the ONLY one that could pull our fat Muslims out of the fire.