One of the main reasons why the Tories remain confident that they will be the largest party after 2015 is that David Cameron continues to lead Ed Miliband as "the best prime minister" (by 35-24 when YouGov last asked the question). By framing the election as a presidential contest, they believe they can erode Labour's poll lead.
But as I argue in my NS politics column this week, such optimism is misplaced. History shows that a well-liked (or, more accurately, less disliked) leader is no guarantee of electoral success. In the final poll before the 1979 election, Jim Callaghan enjoyed a 19-point lead over Margaret Thatcher as "the best prime minister" but the Tories still won a majority of 44 seats. Similarly, in the 1970 election, Harold Wilson's 23-point lead over Ted Heath failed to prevent Labour suffering a decisive defeat.
There is no reason to believe that Cameron's ratings will be enough to offset the toxicity of the Tory brand, not least because he's now been Conservative leader for nearly eight years. As I write in the column, one shadow cabinet minister recently cited Gordon Brown’s "seven years theory" (as distilled in Damian McBride’s memoir) to me as evidence of why Cameron will struggle to deliver a Conservative victory. According to this rule, after a politician has spent this long in the public eye, the voters invariably start to tire of them.
It was after Tony Blair pledged to serve a full third term in 2004 that Brown lamented:
I’ve already had seven years. Once you’ve had seven years, the public start getting sick of you. You’ve got seven years when you’ve got a chance to get people on board, but after that, you’re on the down slope. I’ve tried not to be too exposed, but it’s still seven years. The only chance was getting in next year before the election. Tony knows that. Every year that goes by, the public are going to say: 'Not that guy Brown, we’re tired of him – give us someone new.'
McBride adds: "We talked a while about the 'seven years' theory. It was clearly informed by the US Presidential system, but GB went through a series of British politicians and made the same point. He argued that Margaret Thatcher – despite carefully rationing her public appearances (a point made by Peter Bingle in his Friday musing) – was on the slide in public opinion even at the time of the 1987 election, and that Churchill had only bucked the trend by continually re-inventing himself."
Thatcher and Tony Blair were insulated from defeat by the large majorities they won in their pomp (both losing votes at every general election they fought) but this luxury is not available to Cameron. Unless he can increase the Conservatives’ vote share (as no sitting prime minister has done since 1974, and that only by the means of a second election eight months after a hung parliament), Labour will almost certainly be the largest party after the election. Miliband continues to retain the support of more than a quarter of 2010 Liberal Democrat voters, a swing greater than the cumulative increase in the Conservative vote between 1997 and 2010.
Cameron and George Osborne take inspiration from the Tories’ unlikely triumph in 1992, the first campaign in which they were involved, but they have forgotten one important ingredient: a change of prime minister. It was only after John Major replaced Thatcher in November 1990, just 16 months before the election, that the Conservatives' poll ratings recovered to the point where victory was conceivable.
Will Cameron, who failed to win a majority under exceptionally advantageous circumstances in 2010, be the PM who bucks the seven rule? Don't bet on it.