Only a small number of the DUP's membership will have a vote in any leadership contest to challenge Arlene Foster.
Its eight MPs and 27 of its MLAs will a have a vote.
The party whip is still withdrawn from DUP MLA Jim Wells, so it is unclear if he could also be permitted.
It is also unclear whether House of Lords peers such as deputy leader Nigel Dodds would be able to vote.
However, it means the vast majority of its membership, including more than 120 councillors, will not have a say.
Much of the confusion around the party's internal processes is because the DUP has never had a formal leadership contest.
In its 50-year history, the DUP has only had three leaders - founder Ian Paisley snr, Peter Robinson and Arlene Foster.
The choice of Mr Robinson and Mrs Foster were effectively coronations as they were instated without formal challenge.
Some figures within the party will want to once again avoid an open contest, with the decision instead being thrashed out behind closed doors.
If a formal leadership contest does happen, it is expected those with a vote (the electoral college) will be asked to vote for their preferred candidate.
It is believed the winner must achieve majority support, according to sources.
If no candidate receives a majority, the person with the lowest number of votes will be eliminated and the electoral college will vote again.
This process will continue until one candidate emerges with a majority.
It is expected potential challengers for the party leadership will take some time to declare their hand.
They will likely await further information from party officials on how any formal leadership contest will be carried out.
There is the added complication of Mrs Foster holding the First Minister's role, which can only be occupied by a member of the Stormont Assembly.
It could be the case that the party attempts to split the First Minister and DUP leader positions.
This would allow, for example, a Westminster politician to take on the party leadership and an MLA to focus on the day-to-day running of devolved government.
If a new First Minister is chosen by the DUP, it is expected that Sinn Féin would have to re-nominate Michelle O'Neill as Deputy First Minister.
Some fear this could be problematic, especially if a new DUP leadership seeks to redefine the terms of the current power-sharing mandate.
The next Assembly election is not scheduled until May 2022, but instability at Stormont could lead to an early poll.
