Honestly I don't see it doing anything. People that like him will keep liking him since this is more of a local issue he doesn't have control over with police departments which answer directly to local government.

People that hate him will think of some way of twisting things up to blame him...such as something I saw a little while ago about how he's to blame for some reason for the National Guard or something even though it's Governors that call them in, not the president.