Nasty Political Advertising - Can't the media just say no?

Here in NC we are in the midst of one of the nastiest political campaigns I have ever seen: Sen. Elizabeth Dole vs State Sen,.Kay Hagan, Dole started running ads yesterday accusing Hagan of accepting money from ONE “professional Atheist” which leads to Dole digging up the worst of every possible association with atheists or agnostics, basically saying is not a Christian. Hagan went to court today but there are just six days left.before the election. Are television stations legally obligated to accept anything relating to an election no matter how untrue or how just plain disgusting?