Why the polls are narrowing

Let's start with what the polls are actually showing. The Conservatives level of support has fallen to around 39%. Of the ten polls this month, 7 have put them below forty, when every single poll in October had them at 40 or above, so it's pretty clear they have dropped slightly (though to put this in context, they were polls showing them below 40 in September and almost all of of June). There also appears to have been an increase for Labour, more often than not they are now polling in the high twenties. Despite a couple of big increases in individual polls this month though, their average in November's polls (27%) is actually fractionally down on October (27.6%). Labour are clearly doing better in the polls than they were earlier in the year, but it's a more longstanding advance and we can trace it back to around about conference season.

So, what's causing it? The harsh reality is that voting intention polls only tell us how people say they'd vote. They don't tell us why, or why they might have changed their mind, so the rest of this post is by necessity conjecture.

I should start by knocking down some things that it almost certainly isn't - whenever there is a move in the polls I tend to see comments saying it is the result of the story in the Mirror that morning about David Cameron beating his butler, or the MP for Backwoods West having claimed a plunger on expenses or whatever. I think I spotted one comment saying it wasZac Goldsmith's tax status (a story that came out half way through ComRes's fieldwork and only really got traction once it had finished!). Trivialities do not change the polls, they may have a cumulative effect upon how the parties and politicians are perceived, but taken alone they are not significant factors.

Here's what I see as the four main hypothesis for what is going on:

1) David Cameron's "reverse" on Lisbon has resulted in the Conservatives losing support to UKIP. In theory this seems plausible. Europe is an issue with very low salience as Ipsos MORI's monthly issues monitor repeatedly shows (this month's poll found 3% of people think it is an important issue), however, that tiny minority do care about it a very great deal and it is possible that it would shift their vote. The theory looks very strong if we look at ComRes's polling over the last two months - prior to David Cameron's announcement at the beginning of November they were showing UKIP at around 3% of the vote. In their two polls since then they have shown UKIP at 5% and 6%. However, other polling doesn't back it up - prior to Cameron's announcement YouGov were consistently showing UKIP at 4%, and in their two polls since the announcement UKIP have stuck resolutely at 4%. The other companies have also failed to pick up any great jump in UKIP support. Taken alone ComRes's polls are pretty convincing, looked at in the wider context, I'm not so sure.

2) Increased economic optimism and confidence has brought people back to Labour. On the face of it this would seem a good explanation, the problem comes with the timing. Economic optimism has been strongly recovering since the spring, but hasn't made much further advance in the autumn - yet that's when we saw the narrowing of the gap. Perhaps it is just a slow burner and it takes a while for increased economic confidence to translate into support for the government. If this is the reason, and economic recovery is translating into government support, it raises two very interesting possibilities. Firstly, the formal end of the recession is still to come, and as regular readers will know, I think think that announcement has the potential to have a real impact on public opinion. Secondly, if we cast our minds back to the end of last year, back then we saw the government's popularity increasing on the back of economic confidence, and we saw both of them collapse when a series of high street stories went to the wall in January. Earlier this week there were reports that insolvency practitioners were predicting another wave of closures this January as stores who fail to do well enough over Christmas fold. I'm no economist, so I've no idea how much water that holds - but it suggests we have the potential for further increases... or knocks to consumer confidence in the months ahead.

3) Labour have been performing better. Sometimes it isn't what is happening that affects the polls, it's what hasn't been happening. The Labour party had a pretty good conference, and since then there haven't really been any great plots or infighting, speculation about Brown's future has largely faded, to use their own phrase, they've been getting on with the job. Disunity and incompetence are hugely damaging to a party's image and support, so I think it is quite possible that this is a factor in the narrowing lead.

4) Oh those horrible Tories, run away! Strangely explanations for the narrowing polls I see proposed on blogs and forums tend to more often focus on the Conservatives having done something to drive people away than Labour having done things to win back support. My view is that voting intention will still largely be governed by people's attitudes and opinions of the Labour government, it is a vote against Labour, not in favour of the Conservatives - as the well worn cliche goes, it is governments that lose elections, not oppositions who win them. Most things the opposition parties say and do are probably noticed by very few people anyway. For that reason, and because the Conservatives haven't done anything overwhelmingly disastrous that would impinge on the public consciousness, I think it's far more likely that a better performance from Labour and increased economic optimism are behind their recovery, but as I wrote at the beginning of the piece, we can't tell for sure.