The UK’s political class is in full campaign mode, as Britons go to the polls on 7 May to decide, amongst other things, whether or not the much talked about ‘in/out’ EU referendum will take place.

If David Cameron loses the keys to No. 10 Downing Street, the prospect of a referendum any time soon will recede if not disappear.

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Cameron and Ukip’s Nigel Farage, whose party is expected to win between three and five seats, are the only party leaders to back an in/out vote. Labour’s Ed Miliband has refused to bow to internal party pressure to match the referendum pledge.

Liberal Democrat leader Nick Clegg, whose party will struggle to return half of the 54 MPs it saw elected in 2010, but could still be part of a coalition, continues to oppose an EU vote.

But some liberal party figures have hinted that they might accept a referendum if that’s what it takes to go into a second coalition with the Conservatives.

Last week, Labour lined up former PM Tony Blair to make its case in opposition to a referendum.

Blair asked voters to consider “the chaos produced by the possibility, never mind the reality, of Britain quitting Europe” which would leave “a pall of unpredictability hanging over the British economy.”

“If I was leading a business dependent on access to the single market or, more important, employed in such a business, then the issue of Europe and the risks of this would be a big decider in my vote,” the former prime minister said.

The question of EU membership still appears to interest political leaders and the business community more than ordinary voters.

Immigration is one of the main issues in the campaign, but the role of the EU, as usual, is unlikely to be at the centre of debate. In part, this is because most Britons aren’t that interested in the way the EU works.

It is also because the debate remains as intellectually turgid as ever.

Little EU debate under Cameron

In the two years since his Bloomberg speech on EU reform, Cameron has done little to encourage a substantive debate on the UK’s role in Europe.

Beyond a demand for the UK to be exempted from the reference to “ever closer Union” in the preamble to the EU treaties, and a clampdown on access for EU migrants to welfare and benefits, there is little of substance in his demands.

The government’s “balance of competences” review, unveiled back in summer 2012, was supposed to form the basis for the re-negotiation by setting out the policy areas where EU action was over-reaching.

Whitehall mandarins were asked to conduct a painstaking review into the EU’s activities and assess where there was over-reach and where powers should be clawed back.

But it hasn’t worked out as Cameron would have liked.

Instead, the reports by various government departments have suggested that, while the relationship between the EU and the UK could be reformed, there is no case to repatriate powers from EU to national level.

This is not what Conservative MPs, most of whom want policy competences to be returned to London, wanted to hear.

As a result, the review has, in public relations terms, been a damp squib. The government has effectively hidden it.

It's not the economy

In an interview with the Observer newspaper in March, Lord Boswell, the chairman of the House of Lords EU committee, lamented that the government had “spent £5m of public money on an excellent review and then buried it. People need to know the facts about the UK-EU relationship”.

But the review is not the only example of politicians not telling voters the whole truth in the EU debate.

The Open Europe think tank, a critic of the EU from a free-market perspective, but a supporter of the UK’s membership, reckons that the economic change will be in the range of a 0.8 percent permanent loss to British GDP in 2030 or a 0.6 percent gain.

A worst case scenario, in which the UK is unable to agree a free trade deal with the rest of the EU, would knock 2.2 percent off the country’s economy.

“Brexit is unlikely to be the cataclysmic event some have claimed,” says Open Europe, although it does underline that “Britain will only prosper outside the EU if it is prepared to use its new found freedom to undertake active steps towards trade liberalisation and deregulation.”

It adds that Britain would “need to keep a liberal policy for labour migration” in order to be competitive outside the EU.

In other words, closing the borders, or, at least, making conditions tougher for would-be migrants, will be very expensive.

This might sound appealing to a section of the Conservative party but not to the public who want to see the number of migrants into Britain reduced. Don’t expect any politician to admit that.

Instead, the in/out debate will now boil down to competing economic forecasts - which will produce as many different predictions as there are think tanks and economists - and emotion.

Perhaps this is inevitable, but it’s still no way to make such a monumental decision.