it's like every political party, really. If you are specifically concerned about the press that politcal parties get on here, rest assured it's the same for all of them. Find an opinion and you'll find someone else who disagrees. It might be best to get a real life if you get concerned about the reputation any political party has on a question and answer website!
Anyway, as per the first answer, you'll have to consult your employee handbook, but i would again be surprised if it was expressly banned