The problem is that alot of the hard religious right, especially those in the deep south don't see racism as a problem. They are also some of the ones defending him talking about his daughter and women they way he does. 

However, all but the most ardent supporters are now fleeing from him. It is easy for them to brush off being called a racist. They don't care. It is harder to overlook someone saying the would bang their own daughter, and really hard to explain how you would vote for someone that would "grab them by the p***y".

It is the clarity and the abundance of these messages that are sinking him. Before his racist statements came at month or two month period. These are dropping every day and showing a very dark side to this man. Those already paying close attention were not surprised.