The Uruguayan way to have multiple candidates of one party run in a single-winner election without suffering from vote splitting

Uruguay used to see the use of a single-winner election where a party could run multiple candidates and not suffer from vote splitting.

This is described in Ring's thesis (available online).

He described how when multi-member distrists are used and proportional formulae are used, a party presenting a list of candidates would not be splitting its vote since votes in each district are aggregated at the party level and then the seat won is allocated to the most-popular candidate of the most-popular party.

"Likewise, a similar arrangement can even work in single-member districts:

parties could present more than one candidate or a list of candidates, voters indicate their preferred candidate(s), and party votes would be aggregated: the seat would go to the most-popular candidate within the most popular party." (Shugart 2005, 39-40).

Matthew Shugart explains such a rare case:

For many years, Uruguay was the one national-level example of the use of [a preferential-vote list PR] system in a single-seat district. Presidential elections were conducted by competing party slates, which usually contained more than one candidate. Voters voted for a candidate, but the winner was defined as the candidate with the most votes within the party with the most votes. In this way, uniquely among single-seat district systems, a party could present multiple candidates without fear of dividing its vote and throwing the seat to another party” (Shugart 2005, 39-40).

Although the situation he describes is a presidential contest, it shows that it is possible for parties to offer more than one candidate in a single-seat district without running the risk of splitting the party’s vote, as long as votes in the district are pooled by party.

The party winning a plurality would win the seat.

The candidate of that party with a plurality of votes would occupy the party’s seat.

This way it is possible for parties to offer a choice of candidates in single-seat districts." (Ring, Proportional first past the post (thesis))

However such a practice is not in use anywhere at present.

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The Uruguayan system of "Proportional first past the post" (actually majoritarian FPTP) is known as ley de lemas.

see Wikipedia https://en.wikipedia.org/wiki/Ley_de_lemas

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