"Labour have just spent 13 years sucking up to Rupert Murdoch and George Bush - why would any sane progressive even give them a second glance?
As part of the coalition government, Liberal Democrats have started fixing Labour's economic mess, taking millions of people out of Income Tax and reforming British politics. Things Labour had 13 years to do but failed to deliver.
The Liberal Democrats have also announced more cash for children from disadvantaged backgrounds, one of the biggest moves to improve social mobility in decades.
Continuing that work is something far more attractive to Liberal Democrats than helping Ed Miliband's increasingly desperate attempts to work out what he actually stands for.
However, if he is serious about co-operation then the first thing he should do is stop the Labour Party's attempts to block the referendum on electoral reform that he claims to support."
Farron is at once an obvious and intriguing choice to deliver the message. Intriguing, because he is the most credible leader of the Lib Dem left, and a man whom many regard as a threat to Nick Clegg. Obvious, because this response would be entirely redundant were it to come from Clegg himself, or indeed anyone else on the party's right.
I certainly wouldn't rule out the Lib Dem left sashaying towards Miliband in time. Indeed, Farron even hints at a path to co-operation, by way of electoral reform. But, for now, this response stands – and it is more than aggressive enough to repel, or at least undermine, the Labour leader's advances.