Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Nominating a Successor
The right of nominating a successor had not been possessed by the king, but only by the interrex.(7)
7. Cf. I. V. Prerogatives of the Senate
The consul was in this respect placed on a like footing with the latter; nevertheless, in the event of his not having exercised the power, the interrex stepped in as before, and the necessary continuity of the office subsisted still undiminished under the republican government. The right of nomination, however, was materially restricted in favour of the burgesses, as the consul was bound to procure the assent of the burgesses for the successors designated by him, and, in the sequel, to nominate only those whom the community designated to him.
Through this binding right of proposal the nomination of the ordinary supreme magistrates doubtless in a certain sense passed substantially into the hands of the community; practically, however, there still existed a very considerable distinction between that right of proposal and the right of formal nomination.
The consul conducting the election was by no means a mere returning officer; he could still, e. g. by virtue of his old royal prerogative reject particular candidates and disregard the votes tendered for them; at first he might even limit the choice to a list of candidates proposed by himself; and--what was of still more consequence--when the collegiate consulship was to be supplemented by the dictator, of whom we shall speak immediately, in so supplementing it the community was not consulted, but on the contrary the consul in that case appointed his colleague with the same freedom, wherewith the interrex had once appointed the king.
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Reference address : https://www.ellopos.net/elpenor/rome/2-01-constitution-magistrate.asp?pg=15