The plans were expected to be made public this morning and presented to the Scottish Rugby Union later.
However the team behind the rescue bid decided they required extra time to make final adjustments due to the potential boycott by French and English clubs of the Heineken Cup.
Former Edinburgh director Graham Garvie, who is behind the campaign, believes the offer to save Border Reivers will be accepted by the Scottish Rugby Union on Thursday.
Friday's planned Murrayfield protest against the Magners League club's closure has been cancelled, with Garvie optimistic of an agreement in principle before a meeting of Scottish clubs takes place in Edinburgh this evening.
But it remains unclear when the plans will emerge.
A statement from the newly-formed Supporters' Trust said: "Following the welcome news that the SRU will consider the business case for saving the Reivers provided the case is 'credible', the public publication of the plan has been delayed to ensure that all eventualities have been catered for.
"With the current uncertainty surrounding the Heineken Cup competition, the Borders Supporters' Trust's proposal for the SRU is in the process of being revised to incorporate contingency measures in the event that there is a reduced competition or even no Heineken Cup competition."
Encouraged by SRU president Andy Irvine confirming any offer will be judged on its merits, Garvie has stressed that a takeover will require no funding from the national body.
He said: "Andy has thrown a huge lifeline to the Reivers.
"Fortunately our business plan doesn't require a penny from the SRU, so it looks very much like a deal can be done."
Garvie added: "We hope to have our deal concluded by Thursday evening before the meeting of the Scottish clubs in Edinburgh.
"Now that Andy has agreed to consider our bid it could be a win/win situation for everybody.
"The Borders stays in the pro-rugby business, the SRU saves money, Scotland's three places in the Magners League are secured, the European dimension is clarified and the Scottish rugby fraternity gets some good news to cheer about."
Garvie resigned from his seat on the Edinburgh board to lead the campaign to save Borders.