Worth noting also this from the Guardian's story on it:
This is worth noting. I know picking up Labour votes is the easier proposition at the moment, but frankly, we need to be making some running against Cameron. It's no good soaking up disaffected Labour support only to haemorrhage it right back to the Tories.
Voters are moving away from Labour to a range of opponents, including the Liberal Democrats, who are on 22% today, up three points on last month.
The party is now only six points behind Labour, the narrowest gap since the Liberal Democrats were founded. Support for other parties, 9%, remains strong.
Detailed analysis shows that former Labour voters are transferring their support in almost equal proportions to the Conservative party and the Liberal Democrats, while some established Liberal Democrat voters are transferring to the Conservatives.