Most of the SPL clubs have confirmed they plan to reject the application from Charles Green's Sevco consortium amid strong pressure from their own supporters.
But Doncaster has been trying to persuade Scottish Football League clubs to accept the Ibrox club in the Irn-Bru First Division and it appears the SPL clubs will put off a decision until their lower-league colleagues can make things clearer.
Doncaster told Sky Sports News ahead of the meeting: "There may be a decision, there may not be.
"There was a good meeting yesterday with the Scottish Football League, in which the possibility of Rangers going into the second tier of Scottish football was discussed.
"And ultimately, if that option remains in play, that may be a reason to defer the vote today."
Doncaster added: "It's important clubs don't close off any options.
"They have got the best interests of their own clubs to think about and also the best interests of the game as a whole."
The SPL, SFL and Scottish Football Association executives are all pushing for the First Division package, which also includes merger of the leagues, promotion play-offs to the top flight and a £1million payment for the second tier's television rights.
At least 10 SFL clubs came out against the plan before Tuesday's meeting but all Scottish football clubs have been given stark warnings over the financial implications of Rangers being relaunched in the Third Division.
The document presented to SFL clubs claims £16million would be lost to the Scottish game in such a scenario with all of the SPL's commercial contracts apparently containing an exit clause should Rangers and/or Celtic not be in the league. Fears have been raised that five or six SPL clubs would be forced into administration.
Doncaster said: "There are probably three options for dealing with Rangers. Rangers coming into the SPL with an appropriate range of sanctions is one option. Rangers going into the second tier is another option.
"The option that a lot of people have talked about, Rangers in the fourth tier, ultimately that would wreak huge financial damage on the whole game and it's difficult to see why 41 innocent clubs should pay the price for the misdeeds of one.
"So I think there are really two viable options that are in play at the moment."
Green, whose Sevco firm bought the assets of Rangers for £5.5million when the debt-riddled club was consigned to liquidation last month, was spotted by photographers driving into the underground Hampden car park with Ibrox manager Ally McCoist just before the 10am start.
The other clubs' representatives had arrived before 9am for pre-meeting talks.
Green claimed earlier this week he was confident chairmen would listen to his pleas after meeting several clubs to warn them of the financial implications.
Of the seven clubs who had stated their opposition, only St Johnstone reaffirmed their position on Tuesday after reports claimed Green was attempting to push through an offer that included points deductions, a transfer ban and an apology on behalf of Rangers.
Club chairman Malcolm Murray later issued an "unreserved" apology for the distress caused to Scottish football.
Motherwell were expected to confirm their opposition on Monday after saying a fans ballot would be "used to determine which way the club votes".
They instead announced that Derek Weir, their representative at Hampden meetings in recent months, was stepping down as vice-chairman and from his position on the SPL board.
The result of the vote was eventually announced on Tuesday evening - 82% of shareholders and Well Society members voted 'no' - but the Fir Park board provided no accompanying statement.
Fir Park chief executive Leeann Dempster arrived at Hampden on Wednesday morning.
The clubs have a recent history of procrastination, having twice postponed a vote on financial fair play proposals before coming to a decision in May.
They rejected automatic penalties for newco clubs then but sanctions remain a possibility should Green's club ultimately be accepted.
Doncaster said: "Bear in mind Rangers have already taken a 10-point penalty from ourselves, they are already subject to a three-year ban from European competition.
"They have already got a transfer embargo from the SFA and a six-figure fine, with a prima facie case for dual contracts hanging over them.
"The question is whether sanctions for Rangers coming back into the SPL on top of those already there or whether Rangers go into the second tier."
Hearts, Hibernian, Aberdeen, Dundee United, St Mirren and Inverness were declared objectors along with St Johnstone.
Rangers get a vote with Green needing an 8-4 majority to succeed.
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