YesCymru has announced that it will hold an emergency general meeting (EGM) on December 11.
In an email sent to members, the movement which campaigns for an independent Cymru, said that the EGM will provide members with "the opportunity to decide on the future of Wales' largest political movement".
YesCymru also said that "structures and legal frameworks are now needed to replace the current ones", which they said are "more suited to a small community organisation".
YesCymru has grown significantly in recent years, and now has around 20,000 paid members.
The YesCymru Gweithgor (the working group tasked with drafting a new constitution) has been "working with lawyers to draft their proposals into a robust legal framework" that it will present to members at the EGM.
"Once we've voted on these proposals we can elect a new governing body and return to campaigning for an independent Wales", YesCymru said.