Unease this morning. Is Labour as serious as they pretend about a progressive alliance? Talking to some high-ups on the progressive wing of the Lib Dems, they worry that some the Labour chief negotiators are just going through the motions while putting serious obstacles in the way. They fear many in Labour agree with the neanderthal tendency represented by David Blunkett – no deal is better than giving true proportional representation to the Lib Dems.

This is odd and unexpected: they say Lords Mandelson and Adonis are extraordinarily positive and willing to give most things on the radical Lib Dem agenda. Surprisingly it is those you might think on the left – Harriet Harman, Ed Miliband and Ed Balls who are foot-dragging. This team of negotiators claim Labour can't guarantee to get real PR through the party and none seem keen on it anyway. Their attitude, say my informants, is far from welcoming. The suspicion is they would prefer to sit on the opposition bench and watch the Lib Dems be slaughtered by tying themselves to the Conservatives.

In this febrile moment everyone is jumpy as political life and death negotiations such as these throw up dark suspicions and intense anxiety on all sides. The Lib Dems may be badly misreading Labour's true intent in which case Labour's negotiating team had better hug them tight and reassure them. But if the Labour team really is trying to make a deal impossible, they are making a historic mistake. Worse, they are betraying the people they stand for – every pensioner and poor family who always stand better protected by a left of centre government – however difficult that may be to construct. Is Labour's fatal fascination for a quiet life of internal debate (or strife) on the opposition benches getting the better of them?

They should remember there is no guarantee they wouldn't be out of power for a long time, but the call of the wild is never far from their tribal instincts.

• More election comment from Cif at the polls