Premiership Rugby shareholders are set to vote on participating in European tournaments next season at a meeting in London on Thursday.
Owners and chief executives of the 12 Aviva Premiership clubs - as well as delegates from shareholders Leeds and Bristol - will convene for what has been described as "effectively an emergency meeting" following Ligue Nationale de Rugby's (LNR) announcement last Thursday that French clubs would be withdrawing from a proposed Rugby Champions Cup.
A 10am meeting was called for Thursday by Premiership Rugby, after consulting its clubs at the weekend. The European issue will be top of an agenda that will also include mapping out the future of the game in England over the next five years.
Premiership Rugby has consistently said its clubs will not participate in ERC-run tournaments, with a two-year notice period to quit ERC being completed next June.
Not playing in Europe next season is now a serious possibility with Premiership Rugby's chief executive Mark McCafferty, who will attend Thursday's meeting, admitting at the weekend that was "the most likely outcome".
It is understood that a decision either way is likely to be made on Thursday afternoon.
"This is a critical meeting precipitated by the events of the past week," a club source told Press Association Sport.
"I can't remember a more important meeting for the clubs in the past decade. It is effectively an emergency meeting and after last week's events the size and critical nature of the discussions to take place have been underlined by how quickly it was agreed that all clubs needed to meet.
"I expect that a plan will be made at some point on Thursday. The people that will be in that room are the type of people who will want to move this forward and have a plan in place."
Each club will be represented, with the likes of Leicester chief executive Peter Wheeler, Bath's millionaire owner Bruce Craig and Bristol chairman Chris Booy amongst those set to be in attendance.
Any consensus agreement over the English clubs' involvement in Europe will be agreed to by Premiership Rugby despite its public stance.
The proposed Rugby Champions Cup - formulated by Premiership Rugby and LNR - was undermined last Thursday when the presidents of the French clubs agreed at a meeting at Orly Airport near Paris to commit to the ERC-run format announced by the unions a fortnight ago.
That effectively isolated the English clubs, although beyond 2014/15 LNR said it was seeking the introduction of an alternative competition overseen by a new organisation that will maximise the commercial interests of its clubs.
The LNR's insistence that English clubs should be involved in such a tournament will likely be discussed at Thursday's London meeting. McCafferty suggested last week that he would be willing to listen to the French proposal.
"If somebody can outline what that transition would entail, how the issues would be overcome and exactly what the new structure in 2015-16 would be, then we could look at it," McCafferty told Press Association Sport last week.
"If we can see there is a new structure to replace ERC and we have the detail of that, then something might be feasible. At the moment it's all very general and difficult to comment on."