Mark Drakeford has announced he will stand down as Welsh Labour leader immediately and a leadership contest for a new first minister will be held.
A new party leader will be elected before Easter, Mr Drakeford said in a statement.
Mr Drakeford, 69, the Cardiff West Member of the Senedd (MS), has been first minister for five years.
Speaking at a hastily arranged press conference in the Welsh Parliament, Mr Drakeford said: "When I stood for the leadership, I said that, if elected, I would serve for five years.
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