Any EU referendum should follow re-negotiation, not precede it

Negotiating to see what changes in the terms of the UK's membership of the EU can be secured is surely not something that needs a referendum. It is not a change in our constitutional position; it is simply an exercise to see what change to our constitutional position could be negotiated.  A referendum would be needed only if the Government then decided  to go ahead and implement the changes negotiated.  The only point in having a referendum now would be to ask the single question: should the UK leave the EU now regardless of what changes in the terms of our membership it might theoretically be possible to negotiate?

The Tory backbenchers getting their knickers in a twist about this should change their motion to that end - if in fact getting out is really what they want.  There is no point even in changing the motion just to one calling on the Government to start negotiating now without a referendum, because it is crystal clear that changes to the treaties are going to have to be negotiated anyway to pave the way for the federalisation of the Eurozone.  The time for an in-out referendum will be after those negotiations are concluded.  The Tory leadership is absolutely committed to holding a referendum then anyway, so the backbenchers should just be keeping their powder dry and waiting to demand then that the referendum question includes the get-out option.

Why is it only euro-sceptic Tories who can't see this?