St Mirren on Monday said that they plan to vote against Scottish league reconstruction proposals when a ballot of top-flight clubs takes place next week.
The Scottish league system is currently comprised of a 12-club Premier League and three lower divisions each containing 10 teams.
But the 12 Scottish top-flight clubs are set to vote on plans which would include a merger with the Scottish Football League and the introduction of a 12-12-18 structure.
SPL chief executive Neil Doncaster indicated that league reconstruction could be shelved altogether if his clubs do not back the proposals on April 15, so St Mirren's announcement is a significant setback.
"After a very studied consideration of the Structure, Articles of Association, Rules and Shareholders Agreement, the Board of St Mirren Football Club have decided that they will be unable to support the motion at next Monday's Meeting of SPL Clubs regarding this proposal for League Reconstruction," a St Mirren statement said.
"We also do not accept that this is a take it or leave it situation.
"We do wish to keep working towards one organisation, an all through distribution model and getting closer to our supporters' wishes of a larger league, while being fully aware of the commercial and financial pressures of operating a football club."
It has been reported that 14 Scottish Football League clubs have expressed a desire to delay changes for a further season, with the SFL's own formal vote set to take place next week if SPL clubs give the plans the green-light.