If I were Assange I would stay there until David Cameron or even the Tories are out. But maybe he is tired of staying there and wants to take his chances on the outside.
I would imagine that any political party cannot outright support him. It's pretty much impossible for a government to guarantee no extradition, for example, if there hasn't been an extradition request already made, that's just not how the law works in the UK, but they could possibly make it easier for Assange to feel more trust in the legal process.
Did you know he has 4 children? I didn't know that.
Citation for such a claim?
I realize this is a highly politically charged issue and Assange is a hero to most people (and me) but there is merit to these charges, which will never get cleared up in a court room because of US shenanigans with backdoor rendition hanging like a dark cloud over the whole thing. I can appreciate his work and not his character, just like I can appreciate the Unabomber manifesto argument without endorsing his personal actions.