The club confirmed there were 17,000 renewals in the run up to the opening of the public sale, a drop of 14,000 on last year.
The revenues raised from the season tickets have not been enough to pay off a £1.5m working capital loan from the football club chairman Sandy Easdale and George Letham, a wealthy supporter, which was taken out to avert another financial disaster.
Rangers' 120-day business review warned that, should the club suffer a "substantial decrease" in season- ticket income in the next two months, it would be "unable to trade in the short term" without seeking additional external funding.
The club insisted, however, that the level of renewals and pricing of season tickets reduces the requirement for short-term funding and said the business review showed the club would be looking to raise capital this year.
Earlier this week it was suggested that Rangers International Football Club plc were to launch an £8m share issue within a "few weeks", although no official announcement to the stock exchange has yet been made regarding this.
In his April business review, Graham Wallace, the chief executive, talked of the need to raise up to £30m over three years and the ambition to be Scottish Premiership champions by 2017, with the club entering the Championship this season.
In March, Deloitte, the RIFC plc auditors, stated the uncertainty over season-ticket sales might cast "significant" doubt over the club's ability to continue as a going concern.
One of the key "going concern" assumptions the accountancy firm noted, was that the club would "modestly" increase their season-ticket numbers, which stood at 36,000 in League 1, next season and beyond.
The Union of Fans said the season-ticket slump made it now "obvious" that the fans had "rejected" the board and their running of the club and that in any "normal business" in a few months they would be removed.
The UoF have been telling supporters to commit season-ticket money to the Ibrox 1972 initiative backed by the former Ibrox director Dave King and the ex-Rangers captain Richard Gough. King was unavailable for comment on the development.
"Whilst we do not expect this to happen due to the continued support of anonymous shareholders, who could not care less about Rangers, we would highlight that they have utterly failed to gain crucial trust from fans. We do not believe this trust will ever be built without fundamental change at the club," the fans group said. "It is clear that 17,000 season tickets is not sufficient to see the club through the coming season."
The group were concerned that the board "still refuse" to engage with "the people who care about the club and have the means to improve the financial position greatly".
"It is our firm belief that continued pressure on the board and shareholders will bring about positive change," added the UoF.
They said they would make a final attempt to persuade the board to provide a "legally binding pledge" that they will not sell Ibrox or Murray Park to free up season-ticket funds committed to the Ibrox 1972 fund.
"If they refuse to engage or refuse to provide such a pledge then we will recommend to fans that they continue to support the team but only on a game-by-game basis," the UoF said. "We are aware, however, that many fans simply will not return to Ibrox until there is a change in the power base at the club."
The Sons of Struth fans group added: "I would imagine investors are more than a little concerned and would think an extraordinary general meeting could be called to make changes in the running of the club.
Earlier this week, Easdale, a non-executive director on the RIFC plc board, who controls more than 26% of the company, flew to London for talks with major shareholders including Laxey Partners, Blue Pitch Holdings and Margarita Holdings.