Carwyn Jones' successor will be elected by party members and supporters, after Labour changed its rules at a special conference.
The debate over how Labour elect their next leader has been brought into sharp focus, after Carwyn Jones's decision to stand down as leader and First Minister by the end of the year.
Delegates gathered in Cardiff on Saturday to thrash out how a successor would be chosen, and pressure has been building within the party with arguments that MPs and AMs have too much of a say.
The delegates here decided to back one member, one vote - the so-called OMOV. And this will be seen as a boost to Finance Secretary Mark Drakeford, one of the candidates in the election to succeed Carwyn Jones.
Most pundits think this decision today will give him an edge. Why? Well, because he is very much a supporter of Jeremy Corbyn - somebody who is popular with Labour members.
The other option on the table here was effectively a 50/50 split between members and unions. That's been rejected, which will be seen as a blow to Vaughan Gething, the other confirmed candidate in this leadership race.
OMOV is already used to elect the UK and Scottish leaders, but today will be seen as a boost to Mark Drakeford as he bids to succeed Carwyn Jones.