Grant Shapps said final negotiations needed to take place with the television companies, but added “we are edging towards a solution on this, which is good.”
In an earlier 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.
Proposed dates for the debates are April 2, 16 and 30 - with the final clash coming exactly a week ahead of the May 7
Asked if the PM would now take part in the debates Mr Shapps told BBC 5 Live’s Pienaar’s Politics: “Yeah, I think that’s right. The final negotiation needs to take place with the TV companies.
“I think they are, as David Cameron said, a good innovation.”