Presumably there are those that would want to insist that any Treaty must result in a referendum. I don't see why there needs to be a referendum if he renegotiates. And if he doesn't renegotiate, we shouldn't ratify. It must surely be unthinkable that Cameron could simply pass by the opportunity that a new Treaty obviously presents to renegotiate. Would he really have become Conservative leader if he hadn't been committed to renegotiation? And if he doesn't seek to ratify on this occasion, why would anyone believe he would ever again have any desire for renegotiation?
Conservative MPs need to spell this out in black and white letters three metres high so that Hague and Cameron are left in no doubt: IF YOU DON'T RENEGOTIATE, WE WON'T RATIFY. It's as simple as that.