The pro-single currency campaign, Britain in Europe, faces an exodus of staff, including the expected departure of Simon Buckby, the man who runs it.
The resignations have been prompted by frustration at the Government's failure to take the lead on euro entry and a sense that the campaign had "lost its direction" after the Government's assessment of its five tests for entry in June.
BiE has admitted that several members of its team are moving on. "The political debate has been focusing on everything and anything else," an insider said. "There is no point in our engaging in high-profile activities."
Though campaigners were encouraged by the Government's public commitment to campaign for a "Yes" vote in a future referendum, they were dismayed that there has since been "no real sense about what shape that campaign is going to take".
"It is important to have some idea about that, otherwise we will be campaigning in a vacuum," the source said. "There is some disappointment. I think some people do feel a bit let down, to be honest."
The crisis has prompted the board of Britain in Europe to try to distance itself from the Labour government and return to its roots as a cross-party alliance.
It is felt the campaign will be better able to put its point across if it is not seen as a Blairite organisation, afraid of taking the lead where the Government will not.
BiE insiders claim this rethink has cast doubts over Mr Buckby's future. Some board members are thought to favour the appointment of a dynamic campaigner, one, crucially, with fewer ties to New Labour. Mr Buckby, officially BiE's campaigns director, is a known Labour supporter.
Tensions flared up within BiE amid suggestions from some of its most senior figures that the organisation had failed to make a vigorous enough case for the euro in the run-up to the June announcement on the five tests. Several employees are thought to have quit in protest. Mr Buckby is understood to be considering his position.
He said the June announcement had forced the campaign to "redefine" its position. "After 9 June, you expect a very large number of people who have been working for us for four or five years to start to look for jobs and move on. I am no different to anybody else."
BiE wants to use the approaching party conference season to make its case for euro membership, arguing that the longer entry is delayed, the higher the costs to Britain will be.
It plans to lobby hard for the single currency in an attempt to regain the initiative from the eurosceptic camp, which is raising concerns about the European constitution rather than debating euro membership.Reuse content