Reform is likely to appoint Helen Jenner to take over from Dan Thomas as the party’s Welsh leader, sources have told Wales.
It is understood she is the favourite to replace Thomas, who quit following an arrest on suspicion of assault, and that “very senior” Reform figures had backed her.
Jenner, an MS for Bangor Conwy Môn, is the party’s deputy leader in Wales.
The party’s Senedd group is meeting on Thursday morning to decide if it needs to hold a vote or can appoint someone to the role.
Thomas stood down after he was arrested and bailed by police at the weekend on suspicion of assault and controlling coercive behaviour.
He says he has done nothing wrong.
Thomas has not been suspended and continues to represent Reform in the Senedd as MS for Casnewydd Islwyn.
Jenner is yet to speak publicly about her intentions.
The party’s health spokesperson James Evans claimed on Wednesday he had majority support in the group but decided not to stand after speaking to his family.
If there is more than one candidate it is expected there will be a secret ballot of Reform MSs – but no vote of the membership.
Additional reporting: David Deans