Labour leader Ed Miliband has poured cold water on suggestions that his common front with Nick Clegg against David Cameron on Press regulation could pave the way for a Lab-Lib coalition after the 2015 election, suggesting that Mr Clegg would have to stand down as the head of his party before a pact could be considered.
Although their personal relationship has improved during talks on the Leveson Report, Mr Miliband said he felt that it would be "difficult" to work with the Liberal Democrats in a hung Parliament while Mr Clegg remained leader.
"In this specific area, Nick Clegg took a brave stand. We worked together effectively," Mr Miliband said.
"But it doesn't change my view that the Lib Dems are making very serious mistakes.
"They are not a brake on the Conservatives, they are their accomplices."
Mr Miliband also spoke about the need for Labour to unveil key economic policies. The party plans to set the agenda by bringing forward announcements so they are made before George Osborne unveils another £11.5bn of cuts on June 26.
There is an intense debate about the timing of Labour's policy statements between Mr Miliband and Ed Balls.
The shadow chancellor told Labour's National Executive Committee last week he did not want to make commitments he could not deliver.
Mr Miliband said: "All oppositions face a challenge on economic credibility. We had a financial crisis in 2008 while we were in power and that obviously makes it much harder."