By Ian Dunt
Gordon Brown's calls for a progressive alliance with the Liberal Democrats seem to be dead in the water, with Nick Clegg calling the prime minister desperate.
Mr Brown made his plea in the Independent, where he urged natural voters of the Liberal Democrats and Labour to unite to keep the Conservatives out.
"We have to show people we are in the business of the new politics," he said.
But Mr Clegg shot down the comment with a savage attack on the prime minister in the pages of the Daily Telegraph.
"Brown systematically blocked, and personally blocked, political reform," Mr Clegg said.
"I think he is a desperate politician and I just do not believe him.
"And do I think Labour delivered fairness? No. Do I think the Labour party in its heart has a faith in civil liberties? No. Do I think they've delivered political reform? No. They are clutching at straws."
The comments are a sign of Mr Clegg's increasing confidence as his popularity shoots through the ceiling, but also a direct attempt to neutralise the Conservative attack on his party: 'vote Clegg get Brown'.
It's just the latest signs that embryonic attempts to bring the two parties together ahead of a possible hung parliament were beginning to show cracks.
Children's secretary Ed Balls played down the benefits of a coalition government yesterday, saying: Coalition politics is not the British way of doing government. His view directly contradicts that of home secretary Alan Johnson who called for progressive to counter the opinion that coalition government would be a disaster for Britain.
The spat comes on the same day that a group of generals wrote to the Times backing Mr Clegg's rejection of a like-for-like replacement for Trident.
The Lib Dems are not opposed to a nuclear deterrent per se, but protest the decision to replace the Trident weapons system as it stands, at enormous cost to the taxpayers.
In fact, the generals in the Times appear to go further, saying the nuclear deterrent could be scrapped, with a warning that replacement could threaten front-line forces and global disarmament.
The intervention could not come at a better time for Mr Clegg, who is preparing for tomorrow's TV debate on foreign affairs.
Not everything is going well for the Lib Dem leader, however. Media reports indicate a dossier compiled for him about how to behave in the TV debate was found in the back of a cab overnight.
The dossier goes so far as to suggest Mr Clegg behaves more like Mr Cameron.
"DC [David Cameron] talks a lot in the language of values. We need to do this," it reads.