Originally, the SNP proposed establishing a Scottish Commission to oversee the referendum but, under pressure from other parties, accepted the London-based Electoral Commission would have an input.
Alex Salmond's preferred question – "Do you believe that Scotland should be an independent country?" – has been rejected by opponents as loaded towards a positive response.
In his announcement, the First Minister again pointed to the possibility of a second question on the ballot paper. He looks set to announce his decision on whether there will be one or two questions in the autumn.
Whitehall sources and Mr Salmond's political opponents are convinced he is now minded to have two questions.
SNP politicians respond by saying they were testing public opinion and a decision would be made in due course.
Yesterday, in letters to opposition leaders, Mr Salmond laid out the process he plans to follow, stressing arrangements would be identical to those for other referendums under the 2000 Political Parties, Elections and Referendums Act.
Willie Rennie, the Scottish LibDem leader, said it was disappointing the First Minister had rejected a cross-party initiative to ask electoral experts to help frame the referendum question: "It's important the question is not the gift of a single political party."
Johann Lamont, the Scottish Labour Leader, added: "The door remains open to the First Minister despite his continued resistance to a cross-party approach."