Dave King has played only walk-on roles in what has become an epic Rangers saga, but they tend to be significant.

He re-entered the fray yesterday for the first time in two months, and delivered enough stinging remarks to leave few figures unblemished. He targeted Duff & Phelps, the administrators, Charles Green, the head of the consortium trying to buy the club, and Craig Whyte, the current owner, but mostly he was speaking to the fans.

King has too many of his own troubles to be considered a paragon for the Rangers support. The South African Revenue Services (SARS) filed 322 charges against him, including tax evasion, fraud, racketeering and money laundering. King's shareholding in Rangers – which he bought for £20m in 2000 – is even in the name of his 80-year-old mother, Agnes, and he cannot buy the club himself due to legal restrictions applied because of the SARS case.

Yet many Rangers fans continue to respect King for the investment he made in their club and his own clear emotional ties to Ibrox. They see him as one of their own. Many will consider his strong criticisms of Duff & Phelps, Green, and Whyte as confirmation of their own instinctive wariness about the next chapter in the club's history.

Green has made an £8.5m bid for Rangers, in the form of a loan, at 8% interest, and a Company Voluntary Arrangement proposal will be voted on at a creditors' meeting on Thursday. King is essentially asking fans to be certain that they have faith in the intentions of Green's consortium before they commit to renewing their season tickets. While Green has raised some money for the purchase, there remain doubts about his ability to fund working capital, and King believes that the Yorkshireman and his mostly unidentified group intend to use season ticket revenue to underpin their investment.

Supporters, already wary because of the way Whyte funded his purchase, are reluctant to commit to Green. They are waiting instead to judge him on his actions, but King's statement was in effect a rallying call to be vigilant now.

"I have continued to observe the lack of progress in the attempts to resolve the crisis at Ibrox," King said. "Any offer should demonstrate the capacity to not only acquire the club but to invest going forward. Any offer should be supported by the requisite business skills to ensure that the recent crisis is not repeated. Any offer should recognise that the club has a 'soul', a history, and a tradition going back 140 years. Any offer should recognise the fans are key stakeholders, whether they are shareholders or not.

"In my view, the CVA proposal fails to demonstrate compliance with any of the above criteria. I am opposing the CVA and urge all loyal fans to do the same. We don't want to be back in a similar situation next season. I also believe that all true Rangers fans should not buy any season tickets until full and frank disclosure has been provided by Duff & Phelps, Mr Green, and Mr Whyte, as to what is truly going on behind the scenes."

Neither Duff & Phelps nor Green were hesitant in their responses, with the latter describing King's comments as "scurrilous and scaremongering". Yet King has credibility among the support that Green is trying to claim for himself. His efforts so far have been misjudged, with most fans considering the vote to rename Murray Park as an ill-judged attempt to try to gain the favour of season ticket holders, who would make the decision. Green has also sought to appease fan groups, yet has made several contradictory statements since first emerging as a potential buyer last month.

"I would question Mr King's motives in urging the rejection of the CVA proposal which is the best offer available to creditors, particularly since he made no mention of this or any other issue when I spoke to him on the phone in South Africa last Friday," Green said. "People such as Mr King need to accept the realities of the situation rather than continue to snipe from the sidelines."

In conflating Green and Whyte, King has struck at the heart of the Yorkshireman's problem. He is not a Rangers supporter, so however his deal is structured it is an attempt to take money out of the club having bought it in its moment of crisis. If the CVA vote is passed, King can take his claim about being a creditor to court. Legal action would also be required to adjudicate his claim that Whyte made a verbal agreement to sell King his shares.

"Andrew Ellis [has] advised me that Mr Whyte personally advised him about my first right of refusal but that Mr Ellis had a prior right to 24.9% of the shareholding from Mr Whyte," King said. "Either way, Mr Green cannot acquire the shares. It is unlikely in the extreme that [Whyte] would sell 'his' shares to Mr Green for a nominal sum unless he was obtaining some benefit or retaining some control behind the scenes. It is not my intention to get in the way of a properly structured and a properly funded transaction that meets the needs of all stakeholders, including the fans."

Duff & Phelps refuted the claims, but they too prompt wariness among the fans. King remains an elusive figure, but he still holds a powerful voice.