The bid for an EU referendum could leave a toxic legacy

One of the comments on my previous post on the forthcoming referendum debate asked if the government would have to bring forward a Referendum Bill if a motion calling for one was passed. Technically, no. The motion "calls on" rather than "instructs" the government to prepare a bill. But there would be hell to pay.

And before we reach that point, such a motion would have to be passed. The government affects a relaxed attitude - the 46 Conservative names attached to it on today's order paper are mostly, sniffs one MP, "usual suspects, no major figures among them". But there are three chairs of select committees and a couple of luminaries from the backbench 1922 Committee, including the chairman, Graham Brady. Efforts are under way to add more signatures, and I suspect there are a number of sympathisers who have yet to show their hand.

The proposer, David Nuttall, has included an option for renegotiation of the terms of UK membership in the motion - and that elastic term probably encompasses the views of most Tory MPs. Certainly the majority of the new intake want a substantially different relationship between the UK and the EU - and the emergence of some new EU demand for more powers or money could swing more into Mr Nuttall's camp. Watch out for the leading lights of the big new Eurosceptic group launched last week - the likes of Charlie Elphicke, Chris Heaton-Harris and George Eustice. In an interview for Today in Parliament last Friday, he told me that now was not the right time for a referendum; an alternative relationship with Europe should be devised, so that there was something concrete to put before the voters - probably in the next Parliament.

The government argues that the motion runs counter to official policy - which is to put any further transfer of power to Brussels to a referendum, and no such transfer is contemplated. And they add that it is fantasy to imagine that other EU states will have any appetite to renegotiate the terms of British membership while the Euro crisis rages. Conservative MPs will therefore face a three-line whip against the motion, bolstered (if you can bolster a whip...) with dire warnings of the consequences of defiance. But the career consequences of supporting the government could be painful, too. With the re-organisation of constituency boundaries now in process, the Eurosceptic side argues that MPs would do better to listen to their overwhelmingly Eurosceptic party membership than to their whips. Otherwise they might not be selected for one of the reshaped constituencies. "You can't be a minister if you're out of Parliament," chortles one backer of the motion. This is probably a factor, but it may be that only 30 or so Conservative MPs face "blue on blue" selection battles where they could be rejected by angry Eurosceptic party stalwarts.

And the extent of the rebellion is a moot point if Labour votes with the government and against the motion. Intriguingly, one of the proposers of the motion, alongside Mr Nuttall, is Labour's Keith Vaz, a former Europe Minister. And Euroscepticism is no longer quite the heresy it was in the Labour ranks. But even so, it would be a huge reversal of their normal policy if Ed Miliband were to lead his troops into the Aye Lobby alongside Mr Nuttall and co.

So I don't expect the motion to pass. But the fallout within the Tory ranks and with many of their voters, could be poisonous - which is the real reason why this debate will matter.