First elected to the Senedd in 2011, Zambian-born Vaughan Gething won the Welsh Labour leadership election on Saturday.
Gething is set to be endorsed in the Welsh Parliament as the next first minister on Wednesday.
Gething, 50, succeeds Mark Drakeford, who bowed out with an emotional speech on Tuesday after five years leading the country.
He narrowly won the Welsh Labour leadership election despite concerns over campaign fund sources and financial donations.
On Wednesday afternoon, members of the Senedd (MS) are expected to nominate the new first minister.
If Gething is selected, his name will be sent to the King for approval.
At the debate, the Conservatives and Plaid Cymru are expected to present their leaders – Andrew RT Davies and Rhun ap Iorwerth.
It is a ceremonial move because neither opposition party has enough seats to secure the top job.
Some Labour politicians are unhappy about donations to Gething’s leadership campaign from a company whose owner has been convicted of environmental offences.
Gething’s campaign received £200,000 from Dauson Environmental Group, a business in Gething’s Cardiff South and Penarth constituency.
Some Labour MSs met on Monday night to discuss the donations but it is unlikely they will stop Gething’s nomination because it could lead to a political crisis.
Yesterday, Drakeford appeared in the Senedd for the last time to answer members’ questions.
He said he was “hugely proud” of the 20mph law – a policy that provoked an angry backlash during his final year in office.
Having worked alongside Gething, who was health minister during the pandemic, he said: “I know what a careful and considered person he is when it comes to making decisions.”
After a resignation speech that looked back at the political disorder of Brexit and the Covid crisis, he got a resounding ovation
He paused briefly when he said the past 12 months, during which his wife Clare died, “had been the hardest and saddest of my life”.
Gething will be Wales’ fifth first minister, the first politician from an ethnic minority background in the role and the only black leader of a national government in Europe.