As explained in the inaugural election forecast, up until May next year the Polling Observatory team will be producing a long term forecast for the 2015 General Election, using methods first applied ahead of the 2010 election (and which are also well-established in the United States).

The authors’ method involves trying to make the best use of past polling evidence as a guide to forecast the likeliest support levels for each party in next May’s election, based on current polling, and then using these support levels to estimate the parties’ chances of winning each seat in the Parliament. A seat-based element will be added to this forecast at a later date.

This month’s Polling Observatory reported largely stable electoral preferences during September, despite a turbulent month at the summit of politics. The shares for Labour, the Liberal Democrats and especially the Conservatives declined slightly, the latter by 1.1%. UKIP was the beneficiary, and gained 1.2%, almost exactly what the Conservatives lost. The forecast based on these numbers yet again finds the two major parties locked in a statistical dead heat but with the Conservatives slipping back further, down 1.2% to 33.7%. The gap between the parties widened a little less as our Labour forecast also fell slightly, and now stands at 2.5%.

The inability of the Conservatives to close the gap in voter preferences makes it less and less likely that they can overtake Labour. Our forecast share for them has declined steadily because they are not making the gains in the polls history suggests they ought to be at this stage. Time is running out for Cameron’s party, and unless they can produce a sustained recovery in their polling numbers our forecast will continue to decline.

However, it is worth remembering that swings in the polls are possible even very late in the day, and the gap between the top two remains narrow enough for our forecast to be a statistical dead heat. All signs still point to a very close election.

Things are even worse for the Liberal Democrats, whose  forecast share drops again, by 0.4% to 8.7%.  Should the performance continue, there surely will be consequences for the share of the seats in Parliament as well, specifics of which we are planning to provide in our next post.

In the meantime, we are keeping a close watch on the polls in the wake of the party conferences. Is there a lasting Conservative bounce coming after Cameron’s speech highlighting tax cuts and further reductions in the size of the state? Or will this prove fleeting, as the news agenda moves on to NHS strikes, health scares and foreign entanglements? Only time and the data it reveals will tell.