Confirmed: Ed Miliband will take part in the three leaders' debates during the election . Ed Miliband has said he will take part in all three televised leaders' debate during the election campaign - the day after David Cameron flatly refused. The Labour leader's campaign chairman Douglas Alexander confirmed in a letter to broadcaster that Mr Miliband was prepared to appear. His willingness to appear is in stark contrast with that of Mr Cameron, who last night made it clear he was willing to do one seven-way debate at the end of March, but no more. Meanwhile, the four broadcasters - the BBC, ITV, Sky and Channel 4 - announced they will stick to their previously-announced plans for three debates during the election campaign. In a joint statement, the broadcasters said they would stick to plans for a seven-way debate involving Mr Cameron, Labour's Ed Miliband, Nick Clegg of the Lib Dems and the leaders of the Greens, Ukip, Scottish National Party and Plaid Cymru on ITV on April 2. This would be followed by a second show on BBC featuring the same line-up on April 16 and a final one-on-one clash between the Tory and Labour leaders on Sky News and Channel 4 on April 30 - exactly a week before the May 7 election. They urged the Prime Minister to 'reconsider' his refusal to take part in these shows. But Mr Cameron's chief spin doctor Craig Oliver said their response was 'disappointing' and restated the Prime Minister's 'final position' was for a single debate to take place in the week starting March 23. In a speech to his party's Scottish conference Mr Miliband is expected to say: 'Today the Labour Party has written to the broadcasters saying with or without David Cameron, I will be at the debates. 'And every day up to these debates he [Mr Cameron] will be asked: what are you hiding from?' Mr Miliband is expected to use his conference speech to accuse Mr Cameron of 'duplicity' and of trying to 'chicken out' of the debates. He will say: 'This is what David Cameron used to say about TV election debates: that they were essential to our democracy. Contrast: The Labour leader's confirmation is in contrast to David Cameron's refusal to take part . 'Chicken': Mr Miliband is expected to accuse the Conservative leader of 'running away' in his speech . A Tory-Labour grand coalition could be needed after the election to stop the Scottish National Party holding the balance of power and provoking a constitutional crisis, a former Conservative Home Secretary has said. Lord Baker of Dorking said a deal between the two largest parties could be necessary to ensure the 'continuing unity' of the UK. The former MP said such an agreement could avoid the 'nightmare' of a minority Labour administration depending on SNP support to govern - something which could 'stretch the constitution of our country to breaking point'. Writing in The Independent, the former Cabinet minister accepted that a deal between David Cameron and Ed Miliband was 'quite unthinkable' at the moment, but pointed out it worked in Germany. Lord Baker argued: 'What is at risk is the continuing unity of the United Kingdom. In order to preserve that unity another way should be found. 'This could be a joint government of the Labour and Conservative parties: quite unthinkable at the moment, and at this time likely to be rejected by both of them - but this is what has happened in Germany.' He said it would be possible for the two parties to find areas of agreement - defence, counter-terrorism, infrastructure investment in schools, road, rail and in the reform of skills training and energy - while more controversial manifesto promises would have to wait until 2018. Lord Baker's intervention follows a warning from former prime minister Sir John Major that the SNP would enter any deal with Labour with the 'overriding aim' of 'prising apart' the union. 'That every country apart from Mongolia had them. 'That he wasn't going to have any feeble excuses to get out of debates. 'And now he is doing everything he can to stop them. 'And it is on the issue of leadership debates that David Cameron's duplicity has caught up with him. 'He says this election is all about leadership, all about the choice between him and me, and when it comes to a debate between him and me, he's running scared. 'He's running away. 'I say to David Cameron: You can refuse to face the public, but you can't deny your record. 'You can try to chicken out of the debates, but don't ever again claim that you provide strong leadership. 'You can try to escape the people's debates, but you can't escape the people's verdict.' He will add: 'When all people will see is an empty chair, his claims of leadership will be exposed as empty.' In a letter to Mr Oliver, the broadcasters made clear they were ready to go ahead with the debates even if Mr Cameron decides not to take part - effectively 'empty-chairing' the Prime Minister. But Mr Oliver replied: 'I made the Prime Minister's final position clear in my last letter - he is willing to do a seven-way debate in the week beginning March 23. 'Clearly it is disappointing that you are not prepared to take him up on that offer. 'I am ready to discuss at your convenience the logistics of making the debate we have suggested happen.' With neither side in the stand-off backing down, the debates are set to go ahead without Mr Cameron's participation.
Labour leader said he would take part after David Cameron flatly refused . Number 10 said Prime Minister would only take part in seven-way debate . Broadcasters threaten to go ahead with three leader debates regardless . Mr Miliband expected to say his rival is 'chickening out' of debates today .