Scottish League Two clubs have agreed to back a 14-14-14 structure - meaning any other reconstruction plan would almost certainly falter if they do.
A 15-strong group met twice last week to begin talks over potential changes to the current 12-10-10-10 model.
Should the SPFL remain at 42 clubs and prize money distribution stay the same, any plan would need 75% support.
But no other proposal would get the 15 votes needed in the bottom two tiers if the League Two clubs vote as planned.
The picture shifts slightly if the number of clubs was to be boosted by the introduction of Highland League champions Brora Rangers and Lowland League equivalents Kelty Hearts.
In that scenario, any plan would need the approval of 11 of the 12 Premiership clubs, 17 in total from the top flight and Championship, and 32 of the current 42 in all divisions.
Even then, just one other side would have to vote with those in League Two to scupper the plans.
The option of three divisions of 14 is being given strong consideration by the reconstruction taskforce, but is only expected to be put forward for a vote if at least 11 Premiership clubs support it.
That plan would save Hearts and Partick Thistle from relegation and would mean changing parachute payments, triggering a need to gain that level of backing in any ballot.
The next official meeting of the taskforce is scheduled for later this week.
The reconstruction group, led by Hearts owner Ann Budge and Hamilton Academical vice-chairman Les Gray, was set up by the SPFL in the wake of the resolution being passed to cut short the lower-league campaign.
They met for the first time last Monday and reconvened during the week, when the members brought forward proposals.
|SPFL Reconstruction Group|
|Premiership: Les Gray (Hamilton Academical), Ann Budge (Hearts), Gordon Scott (St Mirren)|
|Championship: Lachlan Cameron (Ayr Utd), John Nelms (Dundee), Dave MacKinnon (Morton), Jacqui Low (Partick Thistle)|
|League One: Paul Hetherington (Airdrie), Gary Deans (Falkirk), Bill Clark (Raith Rovers)|
|League Two: John Sheran (Cove Rangers), Jim Brown (Edinburgh City), Gerry Crawley (Queen's Park)|
|Highland League: Rod Houston Lowland League: George Fraser|
Elgin City chairman Graham Tatters and Stenhousemuir equivalent Iain McMenemy have since confirmed that the League Two clubs met subsequent to that and agreed unanimously that they would only back a 14-14-14 model.
"We've tried to come to a consensus. We're willing to concede things among ourselves and come together," McMenemy told BBC Scotland.
"There are winners and losers in there. Cove would not be moving out of the bottom league, for example, and it wasn't my first choice either but there are times when you have to give."
Both Partick Thistle and Stranraer have been relegated after the decision to end the lower leagues, and Hearts could face a similar fate in the top flight.
McMenemy said it is unfair to demote clubs "in the boardroom instead of on the pitch", but that any changes have to look beyond simply expanding the Premiership.
"Because we have this system of democratic and financial apartheid in Scottish football, unless Premiership clubs support it you're not going to even get it on the table," he added.
"It feels as if the lower leagues don't exist but if they don't take us seriously there is a collective of 10 votes sitting there who want to be listened to or else nothing will go through."
Tatters, meanwhile, warned that some clubs will not survive this lockdown and said that fact would likely render moot any plans to change the composition of the divisions.
"We don't want to change because there is so much more to worry about," the Elgin chairman said.
"In eight weeks, there may not be enough clubs to do it and we'll end up with all these clubs being saved anyway. We're not far away from that, believe me. We've got to start thinking as a unit instead of bunfighting all the time."