Quite a headline on the front cover of today’s Sunday Times. No, not the one that reads “Top Tory ensnared in tax probe.” But the one to the left of it: “No.10 plots early Europe vote in 2016.”

Apparently, Tory advisers are studying the possibility of an EU referendum in 2016, rather than a year later. The idea is that, if the Tories are returned to Government in May, negotiations with other European leaders would continue over the summer, with Cameron revealing the results in a grand statement at this year’s party conference. Then a referendum would take place in 2016. According to one minister, this is “the preferred route”.

The attractions of this route are clear. It would help the Conservatives after the election: two years of constant speculation and uncertainty would be cut down to just one. But it could also help them before then: the very idea of an earlier referendum might persuade some voters that the Tories really mean it. Besides, with Greece in the mire, this might be the time to strike. A poll yesterday found that around half of EU voters support reform.

But tempting paths aren’t always the best ones. And this one has an enormous pitfall not far along it: what could actually be renegotiated in such a short time? The Sunday Times suggests that Philip Hammond has become more “optimistic” since beginning his discussions, but optimism is a gossamer sentiment beside the hard reality of recasting our relationship with the Continent. Even if other European leaders supported the Conservative leadership’s proposals – a very Big If, considering some of Angela Merkel’s recent statements – they still might not be willing to press ahead over this summer. Another effect of the Greek situation is that it likely to sap people’s time and energy.

And then there’s the question of what this says about David Cameron himself. Just put aside your own preferences for a moment, and consider his: apparently, he wants to negotiate the best possible deal for Britain and then use that to campaign for us staying in the European Union. But a rushed job could undo the first part of that equation, and therefore undermine the second. The Prime Minister is in danger of putting the referendum ahead of the renegotiation – and going back on what he’s said before.

Which is always the problem with Cameron. Europe could end up being the new “green crap,” insofar as his position changes with the opinion polls. Some will celebrate that change. Others will lament it. But few will regard the Prime Minister as a politician of any conviction.