VII. Metropolitans are to refer to their Vicar: the mode of electing metropolitans is laid down.
However the metropolitan bishop should refer to you, brother, about the person to be consecrated bishop, and about the consent of the clergy and people: and he should acquaint you with the wishes of the province: that the due celebration of the ordination may be strengthened by your authority also. But to right selections it will be your duty to cause no delay or hindrance, lest the Lord's flocks should remain too long with their shepherd's care.
Moreover when a metropolitan is defunct and another has to be elected in to his place, the bishops of the province must meet together in the metropolitical city: that after the wishes of all the clerics and all the citizens have been sifted, the best man may be chosen from the presbyters of that same church or from the deacons, and you are to be informed of his name by the priests of the province, who will carry out the wishes of his supporters on ascertaining that you agree with their choice. For while we desire proper elections to be hampered by no delays, we yet allow nothing to be done presumptuously without your knowledge.
Source: Letters (New Advent)