Talk to Labour and Tory MPs and it is easy to forget that somebody has to win the general election a year today. Members on both sides are resolutely pessimistic about their side's chances. All they agree on is that, in the words of one Labour source, "it's going to be bloody close".
After the recent narrowing  of the polls, with Labour's average lead down to four points, senior Conservatives are increasingly confident of at least remaining the single largest party next May. But this hope collides with the reality that, though ever-smaller, the opposition's stubborn advantage remains. Not since March 2012, in advance of the omnishambles Budget, have the Conservatives led in an opinion poll.
Were Labour to win by a single point next year (the party's lead in two surveys today), Ed Miliband would almost certainly become prime minister. In 2005, with a vote share of just 35 per cent and a lead of just three points, his party achieved a majority of 66 seats. Five years later, the Tories fell short with a lead of seven. This apparent bias has less to do with the unreformed constituency boundaries than it does with the fact that Labour's vote is far better distributed than the Tories' and that it benefits disproportionately from tactical voting.
Uniform swing calculations can, of course, be an unreliable guide to election outcomes, failing to take into account factors such as the incumbency bonus and above-average swings in marginal seats. Had there been a uniform swing in 2010, the Conservatives would have won  14 fewer seats, Labour eight more and the Lib Dems five more. But even if, as seems likely, the Tories perform disproportionately well in their existing seats, Miliband has a good chance of retaining the lead he needs to win. Crucially for Labour, polling by  Lord Ashcroft suggests that it is winning an above-average swing in its target constituencies. One possibility increasingly discussed in Westminster is that the Tories win the most votes, while Labour wins the most seats (an outcome last seen in February 1974).
The Tories' fortunes are likely to improve as the economic recovery accelerates and as Labour comes under ever-greater scrutiny. But as long as Miliband retains parity with the Conservatives, he has reason to hope. One of the key points in Labour's favour is the unusually low level of switching between the two main parties (just 5 per cent of 2010 Tory voters currently back Labour), with most of the increase in its vote share due to Lib Dem defectors. Unlike in the past, this means that falling support for Labour doesn't automatically translate into rising support for the Tories. In large parts of the country, the Conservatives simply remain too toxic for voters to lend them the support they need to defeat the opposition (no matter how strong the economic recovery). As recent polling by Ipsos MORI showed, 40 per cent would never consider  voting for them, compared to 33 per cent for Labour. Miliband is fishing in a larger pool than Cameron.
The Lib Dem collapse, the Ukip surge, the death of the coalition's boundary changes and Labour's superior ground game are all reasons for Miliband's continuing confidence. Against this is the fact that no party has ever won while trailing on both economic management and on leadership. Cameron leads by 15 points as the "best prime minister"  and the Tories lead by 14 points on the economy  (the highest level so far this parliament). But in this era of stagnant living standards and four-party politics, Labour could yet defy history. The only iron rule of the next election is that there aren't any.