The 12 SPL teams unanimously agreed to back controversial proposals for league reconstruction at a meeting at Hampden yesterday.
Their lower-league counterparts will now consider the move – which could result in the two governing bodies merging – at talks on Thursday.
If the change is given the go-ahead then Rangers, currently 20 points clear in the Irn-Bru Third Division, will remain in the bottom tier in the 2013/14 campaign.
Light Blues supporters are hoping the SFL clubs will refuse to give the green light to move to a system that previously failed in Austria and Switzerland.
Rangers Supporters' Trust board member Mark Dingwall said: "I would hope the SFL clubs look at it very carefully and then reject it. I don't think it's a good move for Scottish football. I don't think this is a good decision by the SPL clubs. I think this move will be disastrous.
"It is an over-complicated and ill-thought-out plan. In fact, it is a panic move by club chairmen who are looking for a financial lifebelt. It will end in tears.
"I think it is a panic move by panicking clubs. Hopefully the SFL clubs will see through the promise of extra payments and reject the proposals.
"The promise of more money from a more even redistribution of funds does beg the question: 'Where is the SPL going to find another £4.2million a year from?'
"The effect for the vast majority of the clubs in the SFL will be minimal. The change doesn't help competition and it doesn't help the fans."
Rangers chief executive Charles Green has questioned why SPL did not vote on reconstruction plans yesterday despite reaching a consensus.
SPL chief executive Neil Doncaster revealed clubs had given their "unanimous backing" to plans for a 12-12-18 structure that would see the body merge with the Scottish Football League, but no formal vote was held.
"I fail to understand why the SPL didn't move to a vote on their 12-12-18 structure," he said.
"After all, SPL chief executive Neil Doncaster is telling everyone agreement was unanimous. So why the delay?
"Might it have been too big a risk to put the format to a vote?
"The SFL clubs meet on Thursday and there has to be the concern that if they don't vote or arrive at any concrete solution then Scottish football could be back in the same situation which caused so much trauma last summer."