MORI/Reuters - CON 37, LAB 41, LDEM 10

Ipsos MORI's monthly political monitor for Reuters has been released. Topline figures are CON 37%(+4), LAB 41%(-2), LDEM 10%(-3).

Two things are worth noting - firstly the importance of turnout here. Almost the whole of this reduction in the Labour lead is down to likelihood to vote. A month ago MORI's figures before their turnout filter were CON 34%, LAB 41%. This month their figures before filtering for turnout were CON 35%, LAB 41%. The reason for the big difference in the published figures is that last month filtering for turnout increased the Labour lead by 3, this month it reduced it by 2.

To take account of turnout MORI include only people who say they are 10/10 certain to vote - this has a much harsher effect than the approach most other companies take, where people are weighted according to how likely they are to vote.

Secondly the Liberal Democrats. Ipsos MORI's February poll was one of the last to show the Lib Dems in the teens, now they too have them at ten. The big variation between pollsters in their reporting of Liberal Democrat support which we saw last year has now largely faded, with the notable exception of ICM.

The most recent figures from each pollster are: Populus 11%, ComRes 11%, YouGov 10%, Ipsos MORI 10%, Angus Reid 10%, ICM 18%. The extreme difference between ICM and the pack is not easily explained - I expect a large amount of it will just be down to random sample variation, and the next ICM poll will be closer to everyone else.