A package of measures giving Welsh Labour greater autonomy from the UK party seems certain to be passed at the Labour conference in Liverpool.
ITV news understands that the biggest union - Unite - has decided to abstain when delegates vote on the proposals.
It means that Welsh Labour will gain control over candidate selection, including of potential MPs.
The Welsh party will also be given a say in what goes into the Westminster election manifesto.
But Unite and other supporters of Jeremy Corbyn were concerned that Carwyn Jones would gain the right to nominate a member of Labour's National Executive.
They fear that would reduce the Labour leader's chances of winning key votes on the party's ruling body.
A series of delegates loyal to Jeremy Corbyn challenged the proposal but others argued that they were putting internal party politics ahead of the interests of Scotland and Wales.