Aside from policy considerations that the President has promoted or proposed, which many approve and many oppose, there are questions of behavior and character that are serious enough to be disqualifying.
Prior to being elected, the President was caught on TV crudely boasting of his sexual escapades.
He has repeatedly been publicly called a moron and worse by many of those whom he appointed to high office and could observe him closely. He has backed a child molester in the recent senate race in Alabama. He has equated some unruly demonstrators in Virginia, with neo-Nazis wielding clubs and protesting removal of confederate statues. He has repeatedly made claims that were easily disprovable, and repeated them when challenged. He has appointed some unqualified hacks who withdrew when their shortcomings were exposed.
In short, he has given ample evidence of being an uninformed boor and an egomaniac. It is perhaps understandable that the Republicans backed him once he won the election. What is really hard to understand is that the voters could ignore the evidence before them and elect him anyway? How could the voters be so blind to these character deficiencies?
Some of us are hoping that he will be impeached and forced out of office before he commits some enormous folly that endangers the nation.