What is the political orientation of those banning “To Kill A Mockingbird” and similar literature?

"To Kill A Mockingbird" has recently been removed from a reading list in a Mississippi school district. (example article)

On Twitter, I've come across US conservatives blaming US liberals and vice versa. Conservatives sometimes claim that liberals are over-reacting to the use of an anti-African-American epithet, while liberals sometimes claim that conservatives dislike the book because of its anti-racism message.

What is the political orientation of those who've removed TKAM from reading lists, removed it from libraries, or made successful or almost successful (e.g. initially successful but then reversed) requests for the book to be removed from reading lists or libraries (as opposed to someone merely trolling people and getting ignored)? Failing instances of TKAM, other books that have been removed with similar rationales (e.g. Huckleberry Finn) would be useful.