Britain's Prime Minister David Cameron speaks during a news conference at the Government Office in Hanoi July 29, 2015. REUTERS/Kham Image Credit: REUTERS

Politicians are always being accused of failing to give straight answers to questions, but they could level the same charge at voters. In opinion polls during the last parliament, thousands were asked who they would support in a general election. A simple enough query, yet many seemed to have answered something different: “Which party do I feel people like me are expected to vote for?”; or “Which big party isn’t currently the government?”

Psychologists call this substitution, and it happens all the time without us realising. Our lazy brains don’t like to process the complex calculations required to find the truest answer, so unconsciously we reach for a simpler, more emotionally available response. To accurately say how you intend to vote means computing many factors — how economically secure do you feel, who do you trust to run the country — and projecting yourself into the experience of making that real-life choice in a polling booth.

It turns out that when those conditions were in place, when it was not a drill, more people voted Conservative than previously said they would. Even after the fact we cannot be sure what question they were really answering. Can you imagine Ed Miliband as prime minister? Does it feel like a changing-the-government kind of a day?

What question voters will answer in David Cameron’s European referendum is an even bigger mystery. The ballot paper will ask: “Should the UK remain a member of EU?” But Cameron’s renegotiation of membership terms is only just getting under way, so even he struggles to say what a ‘yes’ vote would be buying into.

This is not a problem for diehard pro-Europeans and irreconcilable Euro-quitters. They suspect that Cameron’s reforms will be cosmetic, and so their arguments — or rather the questions they want to superimpose on to the ballot paper — are already chosen.

To secure a ‘yes’, ask if we should stick with what we know instead of recklessly gambling with jobs and investment; ask if Britain is an open country at heart and if we want the future to be modelled on something more optimistic than Nigel Farage’s fantasies about the past. To elicit a no, ask whether we should have limitless immigration; whether we want our laws written in Brussels; or if we should hitch our economic wagon to a Eurozone train that looks certain to come off the rails.

Cameron avoids being drawn into the debate on those terms because he has to pretend that his renegotiation will change the substance of the argument. Downing Street refuses to set a date for the referendum, insisting that the timetable can only be dictated by progress in the talks. In theory, the longer the discussions run, the better the deal should get. But June next year has been mooted on the grounds that leaving it any later risks entanglement with French and German elections in 2017, and the danger that the climate in Paris and Berlin will turn less hospitable to United Kingdom demands as domestic political battles loom.

But, in European Union (EU) matters, the patience of Tory MPs is always uppermost in Cameron’s mind. Holding the vote early has the appeal of getting a painful operation out of the way. Lancing the boil will hurt; squeezing it for two years first will hurt more. The downside to a quickie referendum is accelerating talk of the succession. In the last parliament, Tory MPs developed a working assumption that, should Cameron somehow cling on in Downing Street, he would stand down after the EU vote. Winning a majority muted that speculation without eradicating the ambitions that fuelled it.

It is hard for Theresa May or Boris Johnson to start agitating for the prime minister to step aside when he is in the middle of critical talks over Britain’s future in Europe, whereas the completion of talks and the referendum would offer a natural punctuation mark in the parliament for them to start campaigning. In that sense, the likeliest beneficiary of a late referendum is George Osborne — already seen by most MPs as heir apparent. The chancellor of the exchequer has long known that his prospects are inseparable from Cameron’s ability to offer the Tories a European settlement they can stomach. That is why he once considered a move to the Foreign Office, and why he will be touring Europe’s capitals over the coming months, starting with Paris this week.

Osborne has a better grasp than Cameron of what is technically required to secure British interests in a rewired relationship with the EU — the under-the-bonnet business of voting weights and single-market rules. The prime minister’s interest is in securing a symbolic victory to flaunt. The chancellor needs a practical settlement he could work with on making the move to No 10.

The Downing Street duo face the challenge of selling any deal to party and country. The only certainty is that it will include compromises and imperfections — characteristics of the European project that have always been unacceptable to much of right and are rapidly falling out of favour on the left. It is hard to see the radical tendency that is currently mobilising behind Jeremy Corbyn in the Labour leadership contest setting aside partisan hatred for Cameron and Osborne in the interests of preserving Britain’s status as an EU member. Denunciation of a pro-austerity, anti-democracy stitch-up is the likelier trajectory. If Corbyn wins, it is conceivable that the Labour ‘yes’ campaign, chaired by Alan Johnson, will become a refuge for moderates, Blairites in exile, and even they will not want to sound enthusiastic about Cameron’s plan.

Undecided voters can surely be persuaded that Britain is better off staying in the EU, but the prime minister is making that task harder by insisting that the case for yes hinges on the detail of his renegotiation. Asking people if they like the half-baked deal that the prime minister brought home from Brussels seems, in the current climate, to be an invitation to say no.

At some stage, Cameron will have to pivot away from treaty changes and the internal dynamics of the Tory party and make the broader case for Britain in Europe. We know the answer he wants. He is running out of time to give a straight question.

— Guardian News & Media Ltd