The more parties, broadcasters and papers pile in, the greater the danger of a non-agreement.
It would enhance his bargaining power, while the Tories can remind him that they allowed a vote on AV.
The PM recognises how any hint that he could depart could galvanise the "No" campaign - but he is preparing for defeat.
Labour knows the state isn’t perfect. But the coalition is giving power to big corporations, not to people.
The inclusion of the party would help to split the left-wing vote and harm Labour and the Lib Dems.
Aside from his own preservation, any hint that he would depart would aid the Yes campaign.
Labour leader appoints negotiating team and urges the PM to stop "dragging his feet" and sign up to three debates.
Cameron won't repeat Romney's gaffes and enjoys the advantage of incumbency.
Were the debate to be held before the general election campaign begins, the impartiality rules would not apply.
Cameron, Duncan Smith, Gove and Osborne are sincere in their desire for social emancipation. They must now find the words to express it.