In case you think this is "just a mistake", let's look at others that Fox tried to say were Democrats. There was Mark "Party in Your Underaged Pants" Foley. He is misidentified a few times - way past "honest mistake". He was, by the by, a Republican from Florida.
And here.
And then there was the case of the incumbent Senator, who was losing his race. Lincoln Chafee is a Republican, but he was losing - so he must be a Democrat.
Well, we could go on, but why? Once is a whoops (Mark Foley) Twice is lazy (again Mark Foley or Chafee) but 3 times well that is on purpose isn't it?