Nick Clegg has rubbished suggestions that he is leaning towards the Conservatives and would consider a deal with them in the event of a hung Parliament.
In an interview with The Monitor, the Liberal Democrat leader described the idea that the Conservatives were thinking of offering him the job of home secretary in return for co-operation as "pure troublemaking".
It followed the two parties co-operating on voting against 42-day detention, and then Clegg's decision not to run a candidate against David Davis in the Haltemprice and Howden by-election.
In the event of a hung Parliament Clegg said he could not choose between "authoritarian, centralising" Labour and the Conservatives, who "talk the talk [on environmental issues and social fairness] but don't walk the walk."
Clegg is particularly scathing about the Conservatives who he says do not have substantial policies.
"Most people can examine and distinguish between what politicians say and what they do.
"Actually the British public are quite a hard-headed, unsentimental lot and they will judge people by their actions and their policies and not by their rhetoric, their adjectives and verbs.
"They are already quite sceptical about the green credentials of David Cameron.
"This is someone who has talked about the green agenda but has completely backed off the tough choices on how to push forward with the green tax agenda, the cost of flights, and I think people will see that at the next election."
Clegg says that this Tory "plasticity" on environmental issues reflects a wider problem of complacency within the Conservative leadership.
"The more Cameron appears to think the keys to Number 10 are in his hands, the more he appears to think that he doesn't need to bother explaining what he would do when he got there.
"That is a very dangerous place to be because I don't think that people like the hint of complacency that is creeping into the Conservative postures at the moment, where they are not deigning to spell out what they would do in government.
"Power has to be earned, it cannot just be inherited, and that's why I think that over the next two years there will be increasing comparison between our substantive proposals for real change to a clapped-out, discredited Labour government and a plastic, skin-deep appeal to change from David Cameron," Clegg said.
