Ticketus has withdrawn from the Blue Knights consortium and confirmed it will not fund any takeover bid for Rangers.
The London ticketing agency announced its decision in a statement issued on Friday morning, casting further serious doubts over whether the preferred company voluntary agreement (CVA) route out of administration could be achieved.
Ticketus said it had made the move, which will most likely see it become a creditor worth £27m, with its investors' interests at heart.
The firm struck a deal with owner Craig Whyte for licences for future Ibrox season tickets having previously reached a similar arrangement with Sir David Murray when owned Rangers in 2009.
A spokesman for the branch of Octopus investments said: "Ticketus first and foremost has a duty to its investors to protect the investment that it currently has in the club. Our willingness to work with all interested bidders, and to try and be part of a solution for the club, was undertaken with the objective to agree terms that would satisfy both our investors’ needs as well as being in the interests of the club, its fans and its creditors.
"Regrettably over the course of this week it became impossible to reconcile these interests with the proposals put forward by the Blue Knights as the terms of a deal became clearer."
If the Ticketus agreement is now breached and the firm become a creditor of Rangers, it will claim that it is owed at least £27m, according to administrators Duff and Phelps. This would mean it will have the power to defeat a CVA as things stand, meaning liquidation and the newco options would be the only left for the club.
American tow-truck bussiness owner Bill Miller has admitted that a CVA would most likely be defeated if Ticketus was to become a creditor as it would not want to accept a pence in the pound deal.
Meanwhile, it has been reported that former Rangers director and Blue Knights frontman Paul Murray and Sale Sharks Rugby Union Club owner Brian Kennedy - who has had two previous offers rejected by administrators - have been in discussions regarding a possible takeover for the club. A statement is expected from the Rangers administrators Duff and Phelps later on Friday.
Ticketus said that recent events had added to the "complexity of the bidding process" and forced it to back out. The company's spokesman added: "There have been a number of challenging issues that have emerged over the course of the last month, including delays to the administration process, the SPL’s ruling and the recent news from the SFA, all of which have affected the value of the club and added complexity to the bidding process and our discussions with the Blue Knights."
While withdrawing financial backing, Ticketus claimed it remains supportive of the Blue Knights and their efforts to rescue Rangers.
The spokesman commented: "After much hard work from all parties involved, we are deeply disappointed that we are unable to secure an agreement with the Blue Knights. We do not wish to attach any blame to the failure of these talks as, while there have been frustrations on all sides at times, we believe all parties have been acting in good faith to agree terms.
"Paul Murray and the Blue Knights have the interests of the club at heart and we wish them well as they continue to try to secure the best outcome for the club and its fans. We hope that a swift resolution can be found for the club that will enable it to continue to play a leading role in Scottish football."
Ticketus first came to prominence when it emerged Rangers owner Craig Whyte struck a £25.3m deal with the company buying the rights to 100,000 season tickets until 2015.
Mr Whyte subsequently used the money to pay off the club's £18m debt to Lloyds Banking Group after buying Sir David's 85% stake in Rangers for a nominal £1. After Rangers went into administration on February 14, Ticketus started discussions with potential buyers of the club, including the Blue Knights consortium and Singaporean businessman Bill Ng, who fronted a short-lived consortium that expressed an "interest" in taking over the crisis-hit club.
The company backed the Blue Knights' takeover bid for Rangers soon after Duff and Phelps were appointed, while it also supported the group's formal offer that was submitted on April 4.