fox's highest rated show is 4.8 million viewers.
ABC and NBC each get 10 million viewers for nightly news, cbs gets 6 million viewers. CNN and MSNBC have lower ratings, but there are a alot of mainstream-to-liberal sources of news to choose from. Liberals tend to like John Oliver and the Daily Show over fox news.
And the 11 O'clock local news still tends to get a lot of views, I think more than all of those others put together.