Uncertainty continues over debates
There is continued uncertainty over the live televised debates planned for the general election campaign despite a threat by broadcasters to "empty chair" any party leader who refuses to take part in the showdowns.
In a joint statement, the four major broadcasters confirmed plans for a 7-7-2 format, under which two debates hosted by BBC and ITV would feature the leaders of Conservatives, Labour, Liberal Democrats, Ukip, the Greens, Scottish National Party and Plaid Cymru, and a third on Channel 4 and Sky would pit David Cameron against Ed Miliband in a head-to-head clash of the two men most likely to emerge as prime minister.
But the plans were condemned by Ukip leader Nigel Farage who claimed the debates now looked "less likely", the Democratic Unionist Party claimed that the proposal cannot be "legally defended" and the Liberal Democrats said they would continue to push for Nick Clegg to appear in all three events.
The broadcasters said that if any of the leaders decide not to participate, "the debates would take place with those who accepted the invitation".
That raises the prospect of a vacant podium - or "empty chair" - if any of the leaders refuse to participate in the programme.
BBC director general Lord Hall said: "There's nothing in any of our guidelines that says you can't empty chair anybody in any debate."
In an interview with the Radio Times he added: "You have always got to do what is right on behalf of the people who pay for you."
Proposed dates for the debates are April 2, 16 and 30 - with the final clash coming exactly a week ahead of the May 7 poll.
TV executives previously suggested three debates: one head-to-head between David Cameron and Mr Miliband, another also involving Lib Dem leader Mr Clegg, and a third with Ukip's Mr Farage thrown in to the mix.
The change appears designed to overcome Mr Cameron's refusal to take part in any debate that included Mr Farage but not Natalie Bennett of the Green Party - and to reflect a significant public campaign for the inclusion of the environmentalist party, as well as protests from the nationalist parties at their exclusion.
Following talks spanning three months with the main parties, the broadcasters have now issued formal invitations to the leaders to take part.
The empty-chair threat will increase pressure on leaders to participate in the televised showdowns, which were first staged in the 2010 general election campaign. It has traditionally been seen as strategically advisable for incumbent prime ministers to avoid TV debates with their rivals, which were considered to favour challengers.
The proposal has been criticised by Northern Ireland's Democratic Unionist Party, which is the fourth largest group at Westminster, and Sinn Fein, which has five MPs, although they do not take their seats in the Commons.
The DUP's leader, Northern Ireland First Minister Peter Robinson, has written to the broadcasters and Ofcom stating that the proposal is "unacceptable".
He said: "In light of the extension of the debates to smaller and regional parties, the failure of the broadcasters to invite the DUP to participate is inexplicable.
"The broadcasters' decision cannot logically or legally be defended.
Sinn Fein said it would challenge any attempt to discriminate against the party by excluding it.
A party spokesman said: "Sinn Fein will take every opportunity to present and promote its policies and positions."
Mr Farage, who had been the main beneficiary of the original format proposed by the broadcasters, said the revised offer had made the programmes less likely to take place.
"You can't have a debate with seven people on the podium. And if you are going to have seven, you have got to have the Northern Irish DUP, they are after all the fourth biggest party in Parliament," he told Channel 4 News.
"The broadcasters made a decision, Ofcom backed that decision up: there are four major parties in British politics.
"Mr Cameron, I'm afraid, has managed to upset the whole debate, to dilute the thing. And I think these debates are now looking less likely to happen than they were before."
A Labour spokesman made clear that Mr Miliband is ready to take part in all three debates.
"We will debate anyone the broadcasters choose to invite and we are pleased to see the clear proposal to have three debates all in the general election campaign," said the spokesman.
"The broadcasters have obviously made a very significant move to adopt wholesale the Prime Minister's proposals and it is surely now not possible for him to maintain his opposition to participating in these debates.
"We relish the opportunity for Ed Miliband to take on David Cameron directly in a head-to-head debate."
The Tories would not be drawn on whether Mr Cameron would take part, with a spokesman saying: "These new proposals are being considered as part of the ongoing discussions about the debates".
A Lib Dem spokesman said: "We have always been in favour of TV debates and are committed to making them happen but want to continue discussing the most recently proposed format.
"We have always been clear that as a party of government, we must be able to defend our record in all the TV debates."
Lib Dem minister Steve Webb said despite the party's desire for Mr Clegg to be in all the debates, "when push comes to shove we will participate".
The SNP and Greens, who had been excluded from the original format, welcomed the new proposals.
SNP leader Nicola Sturgeon said: "With a larger membership than the Lib Dems and Ukip combined, and more elected MPs than Ukip, the case for including the SNP in the televised debates was unanswerable."
Ms Bennett said: "The decision to include the Greens in two debates is an acceptance by the broadcasters that we now are in an age of multi-party politics."