I have seen a number of people, not just MPs or candidates do this lately. When you are using a hashtags, punctuation of any form breaks up the hashtag.
So if you are going to try and create hashtags, make sure they don’t contain punctuation. Twitter, and hashtags in particular, doesn’t really place a lot of weight on correct grammar. It is about getting a message across, and hashtags are to hep with searches. So stop trying to apply grammar and punctuation to them.