EDIT: Another interesting observation I've heard is that people who have been close to the presidency, those who have a better idea of the day to day of what it's like to be president, almost all say Trump is completely inadequate. Of the five living former presidents not one supports him. A presidential candidate not having support from former presidents of their party has never happened before. Almost all former staff from previous Republican administrations, people who worked with the president every day, do not support Trump. Even Ari Fleischer who was one of the few from the Bush administration to support Trump now says he'll leave the ballot blank.