Prime Minister David Cameron is refusing to take part in the schedule of general election leader debates put forward by broadcasters.
Instead he has put forward his own proposal for one debate involving seven party leaders to take place in three weeks’ time.
Broadcasters had agreed to host three debates in the month before the 7 May general election: two featuring seven party leaders and one featuring just Miliband and Cameron.
Now Cameron has offered to take part in one debate – with the leaders of Plaid Cymru, UKIP, the Lib Dems, Labour, Greens and SNP – in the week beginning 23 March.
Downing Street director of communications Craig Oliver said in a letter to broadcasters: “This is our final offer. Given this has been a deeply unsatisfactory process and we are within a month of the short campaign, the Prime Minister will not be participating in more than one debate.”
Meanwhile, Lib Dem leader Nick Clegg is said to be willing to take David Cameron’s place in a head to head TV debate with Ed Miliband.
Former Lib Dem leader Lord Ashdown told BBC Radio 4's Today programme: "I'm told that Downing Street is now depending on the Liberal Democrats to say no. Well, I've got bad news for them. We're not going to.
"I hope the broadcasters stand firm, but I need to be very clear that even if it is done in the fashion that the Prime Minister demands – and why on earth should he be able to veto the democratic debate? – we will still be there."
Lord Ashdown added: "If it is the case that there's a two-headed debate and Mr Miliband turns up and the Prime Minister will not defend the record of the Government, then Nick Clegg will be very happy to."