Party members voted on a motion authorising senior figures to negotiate with Labour on agreeing a final number and changing the electoral system.
It marks a step towards a vote in the Senedd which will increase the number of members from the current 60 following a decision by delegates to Welsh Labour’s conference recently to back similar proposals.
Any change in the number of MSs and voting system must be backed by a ‘super-majority’ of two-thirds of members of the Welsh Parliament.
Between them, Labour and Plaid Cymru have that many votes and increasing the size of the Senedd is one of the commitments included in the government deal between the two parties.
Now they will begin negotiations aimed at settling on a specific number and what sort of electoral system would be preferred.
Consensus is likely to settle at between 80 and 100 members chosen via an electoral system that includes some element of proportional representation.
The Welsh Conservatives are vehemently opposed to any increase.
A spokesperson said that “to focus on creating more politicians when the cost of living is on the up is self-indulgent and a slap in the face for those who are in real need.
“We’d expect nothing less of Plaid Cymru”
Following the earlier Labour conference vote, the Opposition leader Andrew RT Davies tweeted that “Wales doesn’t need more Senedd Members. Wales needs proper governance.
“1 in 4 people in Wales are on a waiting list. That is because of Labour mismanagement, and no amount of constitutional navel gazing will solve that.”
At this conference, Plaid Cymru has been doing a certain amount of questioning of itself, about what it is for and in what direction it should be heading.
When Adam Price took the leadership from Leanne Wood in 2018 it was with the promise of reinvigorating the party and leading it to its long-hoped-for breakthrough.
That hasn’t yet happened and last year’s Senedd election was another disappointment for Plaid Cymru which lost Leanne Wood’s totemic Rhondda seat and left it as the third party in the Welsh parliament.
In his conference speech, Adam Price acknowledged that disappointment but urged members to focus on what had been achieved by signing a co-operation agreement with Labour. “We didn’t win the election. But as so often in our history we dusted ourselves down and resolved to win the argument instead.
“We snatched our moral victory from the mawing jaws of defeat. On Free school meals. On Rent Control. On tourism levies and second home taxes. On a National Care Service. On free childcare for two year olds.”
That’s why free school meals has been put front and centre of this conference because it illustrates for members and for those looking on from outside the Plaid Cymru leader’s view that the party is able to achieve tangible change.