Election debates: Clegg says David Cameron being ludicrous
Deputy Prime Minister Nick Clegg has criticised David Cameron's "ludicrous" tactics over the televised debates planned ahead of the general election.
The Lib Dem leader said Mr Cameron was "ducking and weaving, using other people as an alibi".
The PM has suggested the Democratic Unionist Party should be invited, having previously called for the Green Party to be included.
Revised plans from broadcasters would see two debates with seven parties.
The Green Party, UKIP, the SNP and Plaid Cymru would join Labour, the Conservatives and the Lib Dems in debates hosted by the BBC and ITV.
The other one, hosted by Sky and Channel 4, would be a head-to-head between Mr Cameron and Labour leader Ed Miliband.
Mr Cameron, who has said he wants the debates to go ahead, urged a rethink when the Greens were left out of the initial proposals, saying it was unfair for UKIP to be included but not Natalie Bennett's party.
After the new proposals were unveiled, he said he would be "delighted" to take part but did not understand, if Scottish and Welsh parties were included, why parties from Northern Ireland were not included.
On Tuesday he said "yes" when asked if he would take part if Northern Ireland parties were included, but in a later interview with Jeremy Vine on BBC Radio 2 he said he wanted the debates to take place before the election campaign started in earnest.
This was because he thought that they dominated coverage too much if they were held during the official campaign - which runs from 30 March.
On his LBC phone-in on Thursday, Mr Clegg, who wants to be included in all three debates, said the Conservatives' behaviour was "frankly increasingly laughable".
"I suspect next week he will be worried about the fate of the Monster Raving Loony Party, and after that, when they're in, possibly the tea lady as well, why is she not in the debates," he said.
"Why don't we just have everybody? It's just getting ludicrous."
He also questioned how a debate would be organised with so many people on the panel.
"By the time everyone's finished their one-minute introduction, the whole nation will have switched over to Coronation Street."
On Wednesday, Lib Dem minister Simon Hughes predicted the debates "probably" wouldn't go ahead because of the difficulty in finding agreement.
Labour leader Ed Miliband said Mr Cameron was "wriggling".
He added: "It's like the dog ate my homework excuse - a new excuse every day about why he doesn't want these to happen."
The broadcasters have rejected the DUP's request to be included.
In a joint statement, BBC, Sky and ITN said allowing only one of the Northern Irish parties to take part "would be unfair and discriminatory".
The proposed schedule is for debates to be held on 2 April, 16 April and 30 April in the run-up to the 7 May election.