zombie issue
A "zombie issue" is one that is a dead issue for most people but that some people won't allow to stay dead. They keep rehashing it and refusing to accept the resolution of the issue that most people have seen to be reasonable. They usually do this in an attempt to gain political advantage over their opponents, criticism of whom is the purpose of keeping the issue alive, or simply to draw attention to themselves. They don't realize that most people think their either deranged or just jerks for not letting the issue stay dead.
Joe: "I'm tired of hearing about the Benghazi tragedy and what Susan Rice said about it afterward, man! It's a zombie issue, and I wish those complainers would just let it stay dead."