Rhun ap Iorwerth has been voted first minister of Wales after Plaid Cymru’s Senedd electoral victory ended 100 years of Labour hegemony and held off Reform UK.

Ap Iorwerth was confirmed after a plenary vote on Tuesday with the support of the 43 Senedd members of his party and two Greens.

Plaid Cymru ended Labour’s century-long electoral dominance in Wales in last week’s elections, winning the most seats in the newly expanded 96-seat parliament. Reform, which had hoped to be the biggest party, won 34 seats, and Labour came third with just nine seats, marking a definitive end to the party’s grip on its birthplace.

The former Labour first minister Eluned Morgan lost her seat, triggering a leadership contest. Ken Skates, the Senedd member for Fflint Wrecsam and former cabinet secretary for transport, has taken over as interim leader.

Under Wales’s new and more representative electoral system, at least 49 seats are needed for a majority. No party was likely to win that, but Friday’s results put Plaid Cymru in a comfortable position to form a minority government.

Ap Iorwerth previously told the Guardian he would seek out mature cooperation from all opposition parties on a case-by-case basis, and that his administration would press the UK government for extra powers over policy areas such as policing and justice, rather than engaging in political rows with Westminster.

Plaid Cymru has ruled out an independence referendum in the next Senedd term, but the party has repeatedly said it will use its time in government to make the case for an independent Wales.

The Senedd also voted Labour’s deputy leader, Huw Irranca-Davies, as the new Llywydd, or presiding officer, before the first minister vote. Ap Iorwerth is expected to begin appointing cabinet secretaries on Tuesday afternoon.

More details soon …