Rumours of an upcoming Nick Clegg assault on eurosceptics are picking up pace this morning, as he attempts to wrestle back the political agenda ahead of European elections.
The deputy prime minister is planning to take on Nigel Farage in a one-on-one debate on the EU and block any attempt by Downing Street to replace Baroness Ashton with a eurosceptic right-winger as EU commissioner.
"I'll tell you what I’ll do. I will challenge Nigel Farage to a public, open debate about whether we should be in or out of the European Union," Clegg said during his weekly phone-in show on LBC this morning.
"That’s the choice facing the British people.
"He is the leader of the party of 'out', I am the leader of the party of 'in'. It’s time for a proper public debate so that the public can listen to the arguments and decide for themselves."
The prospect of a Farage-Clegg debate will have proved mouth-watering for many Westminster observers but it puts both men in a potentially dangerous position.
Should Clegg be perceived to have lost the debate he will be accused of handing Farage the credibility he so desperately desires.
But some feel that Farage could find himself out of his depth once faced with sustained factual questioning in which he is unable to fall back on his cheerful public persona.
The rumoured decision to call for a debate is the latest step in the Liberal Democrat strategy of committing to a pro-EU platform at the next election.
With the Tories suffering internal warfare over the EU and Labour unwilling to make a public case for its defence, Clegg feels he can hoover up those few pro-EU votes which do exist.
Such a move would compliment his attempt to portray himself as a moderate centrist, in contrast with Labour and the Tories, going into the next election.
"He is leader of the party of out, I am leader of the party of in," he said on LBC.
Meanwhile, Clegg is weighing up what could become an extraordinary political row, with the emergence of threats to block Tory efforts to install a eurosceptic as Britain's next EU commissioner.
Some expected Liam Fox, who recently settled his libel case over the Adam Werritty scandal, to be put forward for the role. Others have mentioned Owen Paterson, the current controversial environment secretary, or Peter Lilley.
Liberal Democrats would be more sympathetic toward a figure like Andrew Mitchell, who is ready for a return to frontline politics following the 'plebgate' row, or Andrew Lansley, the current leader of the House.
"We don't think it would be in Britain’s interest to use the job as a bully pulpit to attack Brussels rather than working constructively to protect our interests," a source told both newspapers.
Cameron will be weighing up the various possibilities warily, as he seeks to prevent himself being caught between mutually incompatible demands from Tory backbenchers and the Lib Dems.
There are also concerns in the Tory party that using a Tory MP for the role would trigger a by-election, potentially allowing Ukip a serious boost ahead of the 2015 general election.
Cameron may be tempted to sidestep the row and focus on getting a business leader into the economic portfolio, rather than Ashton's foreign affair's brief.