UPDATE: Labour lead at 2: Lab 33%, Con 31%, UKIP 15%, Lib Dems 8% Green 7%

Source: Channel 4 news

The Labour Party extends its lead to 2% in this week's opinion poll aggregate. The Tories fall by 2%, UKIP are down by 1%, the Lib Dems hold steady and are up by 1 point to 8%, and Labour remain on 33%.

The polls this week have ranged from a 7% Labour lead to a 4% Tory lead. Whilst the majority of polls have had a small Labour lead, reflected in my weekly polling aggregate, the fact that there is such a wide variation highlights the unprecedented volatility of the situation we currently find ourselves in. In my view, the two parties are running so close together, which is why you get polls on both sides, but I could be wrong. The same is almost certainly true for the Liberal Democrats and Green Party. The major polling story is the continued decline of UKIP, down to its lowest ever share in my weekly polling aggregates, perhaps due to a recent sex scandal and the furore over Neil Hamilton's selection, which looks to have damaged the party. Nigel Farage, the UKIP leader, has also seen his popularity plummet over the same timescale.

Meanwhile, a YouGov opinion poll says that 1/3rd of Green supporters will be voting Labour at the next election. This shows that Labour may be on course to squeeze the Greens in 2015. This is significant, and there are two major reasons for this shift. Number 1 is that the Green Party is smaller than the other 4 major parties, and so cannot stand candidates in all GB constituencies. Number 2 is that Labour's rallying cry against the Tories may also have some sort of effect. As Stephen Shakespeare of YouGov duly notes:

"Using YouGov’s First Verdict instant polling platform, with a large sample (4,335), I asked: 'Which party would you most like to win in your constituency? Please choose the party you like best, regardless of whether they have a chance of winning​.' I followed up with: 'How do you predict you will actually end up voting? This may not be for your favourite party but for your tactical choice'. There was some movement to and from all parties, but just one example of real significance: a third of the Green vote went to Labour. If we think this will hold, then we should factor in a couple more percentage points for Labour. Of course there may be even more from Ukip back to the Conservatives, but we didn’t see it in this experiment."

Due to this, there is a significant chance that Labour may end the election campaign with a higher share of the vote than when it started. Whilst this is encouraging for Labour, we must also keep in mind that around 35-40% of UKIP voters are currently undecided about which way to vote, and they could break decisively for the Tories. Therefore, the result of the general election may depend entirely upon which party can squeeze support better from the smaller parties. Labour must squeeze the Greens and SNP, whilst the Tories will hope to win back a majority of UKIP supporters.