[Gay State Conservative]

If he's got enough votes to win (which he does), then there wouldn't be nearly enough support for any challenge to him as a result of not holding a vote.

But if support was weak (or worse) within Labour,couldn't he be tossed overboard by his own Party?

I do recall Cameron having said that if it came to a vote,Blair could count on support from the Tories during Question Time a week or two ago.

[Canard]

" But if support was weak (or worse) within Labour,couldn't he be tossed overboard by his own Party?"

Yes he could. But (a) this could equally happen at any point for any (or no) reason if they so wanted irrespective of whether a vote is held on this issue and (b) there probably isn't massive opposition to this in the Labour Party, no more so than on several other issues anyway.