"Certain Labour Party big beasts, and they know who they are, are already experiencing more activity on the ground from us. We are going to make Ed Balls and Alistair Darling and some of their ministerial colleagues feel very uncomfortable.
They will not only be fighting their most difficult general election campaign on a national front in two decades but they will also have really tricky contests in their own constituencies."
You can understand the thinking behind this. The Tories hope to divert these ministers from their government work and get them mired in tight (and costly) constituency battles. And, should it come off, then it could theoretically worsen Labour's post-election malaise - although, as Tim Montgomerie says, it may actually be better for the Tories if Ed Balls is left in place.
But I can't help but think that "senior shadow cabinet source" made a mistake in admitting all this to the papers. Given the majorities the Tories have overcome in recent by-elections, the seats in question are potentially winnable. But to suggest - rightly or wrongly - that ministers are being targeted, over and above the Tories' marginal constituency campaigning, risks sounding tribalist and perhaps even triumphalist. In the current climate, the Tories should be going around saying that they want to win for the good of the country - not that they're indulging in political assassinations.