A surprising ICM poll in tomorrow’s Guardian puts Labour back ahead with a good 3 point lead – a reversal of last months figures: CON 34% (-3), LAB 37%(+3), LDEM 21% (nc).
Voting intention polls tend to shift for identifiable reasons – Charlie Kennedy is ousted as party leader and the Lib Dems go down; Tories get a new leader they go up; fuel strikes bring country to a standstill Labour go down, and so on. Big shifts like this with no obvious reason are unusual, the Conservatives haven’t done anything particularly damaging in the last few weeks and most of the media coverage of Labour has been about financial “sleaze” and internal divisions over the education bill – hardly the sort of thing that is liable to improve Labour’s popularity.
It could be that the poll is simply a rogue or even just a change within the margin of error, but along with YouGov ICM do tend to produce the most steady and robust figures. Two potential explanations come to mind – firstly the Ming effect. While the headline level of Liberal Democrat support is unchanged, there could be underlying churn – perhaps Sir Menzies Campbell’s election has taken support from the Tories but lost support to Labour. An alternate explanation is that Cameron’s honeymoon has simply come to an aprupt end, that the Tory increase was a purely temporary phenomenon and they are now falling back to their previous level of support.
Some recent polls have shown a slight move back to Labour – Populus’s last poll showed the Tories slipping back, as did MORI’s. The exception at the moment is YouGov, who last month reported the Tories moving back ahead of Labour. The next couple of polls will confirm whether this is a genuine swing back to Labour or just normal variation.