A bid to reach a consensus on green issues between David Cameron's Tories and Sir Menzies Campbell's Lib Dems may have fallen at the first hurdle.
The two leaders are still supposed to be meeting
The Conservatives reacted angrily to Lib Dem claims they will use a meeting between the two leaders to test the extent of Mr Cameron's green beliefs.
While a Tory environment spokesman accused his Lib Dem counterpart of "playing politics" with climate change.
There is also some dispute over who actually called the meeting.
Tory spokesman Peter Ainsworth said: "It is disappointing that [Lib Dem environment spokesman] Chris Huhne has chosen to play party politics with the serious issue of climate change.
"We will continue to work constructively with politicians from any other party that is prepared to put the environment at the very top of its agenda."
The Conservatives maintain they called the meeting between the two leaders but the Lib Dems say it was in response to a challenge by Sir Menzies during the recent local election campaign.
Mr Huhne meanwhile claimed there had been a "string of contradictions" between Mr Cameron's "green words and his party's blue actions".
"The Liberal Democrats are very much in favour of the cross-party agreement on climate change. People want parties to work together on solutions to the pre-eminent challenge of our time," said Mr Huhne.
"We believe that the cross-party agreement can, in principle, make it easier for parties to propose difficult measures that could otherwise fall apart in the face of vocal but minority opposition.
"However, it is important that the parties who are signed up have faith in each others' fundamental commitment to the long-term goals. Otherwise there can be the worry that it is being used as a camouflage for not taking decisions, rather than a way of taking tougher ones."
The Lib Dems want to know where Mr Cameron stands on key issues such as nuclear energy and vehicle excise duty.
There is a climate change agreement between Tories, Lib Dems, the SNP, DUP and Plaid Cymru.
"For the consensus to work we need clear policy commitments from David Cameron's Tories, not just warm words," added Mr Huhne.