What preferential voting is — how third-place ballots pick the winner
Preferential voting asks voters to rank candidates rather than choose one. If no candidate holds a majority of first preferences, the lowest-placed candidate is eliminated and the second preferences on their ballots are transferred to the survivors, and the count is run again
The three lines
- The rule — eliminate the lowest candidate and transfer their next preferences until someone has a majority
- The purpose — produce a majority winner without holding a second round of voting on another day
- A live example — Kim Min-seok's 54.08% in Korea's Democratic Party leadership race on August 17, 2026
Key questions
- How is preferential voting counted?
- First preferences are counted alone. If a candidate has more than 50%, the count ends. If not, the candidate with the fewest first preferences is eliminated, their ballots are re-examined, and each one's second preference is added to whichever surviving candidate it names. The count is run again. With three candidates, a single transfer always leaves two, and two candidates always produce a majority barring an exact tie.
- How is this different from a runoff election?
- The logic is the same; the procedure differs. A runoff holds a second vote on a later date between the top two. Preferential voting collects that second choice in advance, on the original ballot — which is why it is also called instant-runoff voting. It costs less, finishes sooner, and avoids the lower turnout that second rounds often suffer. The trade-off is that voters cannot react to the first-round result.
- Is my vote wasted if I rank a third-place candidate first?
- No, and avoiding that outcome is the point of the system. Under a single-choice ballot, backing a third-place candidate has no effect on the result. Under preferential voting, when that candidate is eliminated your second preference is counted for a surviving candidate instead. The exception is a ballot left blank beyond the first preference, which is exhausted and stops there.
The result of South Korea's ruling-party leadership race on August 17, 2026 was Kim Min-seok 54.08%, Jung Chung-rae 45.92%.
But Kim did not hold a majority of first preferences. His cumulative share through the regional rounds was 49.91% — short of 50% by 0.09 of a point.
No majority, yet a published 54.08%. Preferential voting sits in between.
1. The rule is two lines long
Preferential voting asks voters to rank candidates rather than pick one. The Democratic Party of Korea uses a ballot allowing up to three ranked choices when three or more candidates stand.
The counting rule:
- Count first preferences only. If someone clears 50%, stop.
- If not, eliminate the lowest and add the second preferences from their ballots to the survivors.
With three candidates, one transfer leaves two. Two candidates always produce a majority unless they tie exactly. The system therefore always manufactures a majority winner.
| Stage | Action | Ends when |
|---|---|---|
| First count | Count every ballot's first preference | A candidate exceeds 50% |
| Elimination | Remove the candidate with fewest first preferences | — |
| Transfer | Add those ballots' second preferences to survivors | — |
| Recount | Count again | A majority appears, else eliminate again |
2. Following the arithmetic
To make the mechanism concrete, here is a worked example. These numbers are invented for illustration and are not real election data.
Assume 100 ballots and three candidates, A, B and C.
First count
| Candidate | First preferences | Share |
|---|---|---|
| A | 45 | 45% |
| B | 40 | 40% |
| C | 15 | 15% |
Nobody has 51. C is lowest and is eliminated.
Transfer — C's 15 ballots are re-examined for their second preference. Suppose 11 name A and 4 name B.
Recount
| Candidate | First count | Transferred | Total | Share |
|---|---|---|---|---|
| A | 45 | +11 | 56 | 56% |
| B | 40 | +4 | 44 | 44% |
A has a majority. The count ends.
Note what happened: A polled 45% and is published as 56%. The 54.08% announced on August 17 is a number of exactly this kind — not a first-preference share, but a post-transfer total.
3. Preferential voting versus a runoff
The logic is identical. The procedure is not.
| Aspect | Runoff | Preferential voting |
|---|---|---|
| Rounds of voting | Two, on separate dates | One |
| When the second choice is made | After seeing round-one results | In advance, on the ballot |
| Cost and duration | Two elections | One |
| Second-round turnout | Frequently lower than the first | Not applicable |
| Reacting to results | Coalitions can form between rounds | Impossible — preferences are sealed |
This is why the method is also called instant-runoff voting: it asks "who would you back in a runoff?" on the original ballot.
The last row is where the two genuinely diverge. In a runoff system, the fortnight between rounds is spent courting the eliminated candidate's supporters. Under preferential voting there is no such interval. The second choice is already inside the envelope.
4. What happened on August 17
| Item | Detail |
|---|---|
| Eliminated third candidate | Song Young-gil |
| Transferred votes | Second preferences on Song's ballots |
| Published result | Kim Min-seok 54.08%, Jung Chung-rae 45.92% |
The structure was understood in advance. Digital Times headlined the point in early August: with no first-round majority, Kim benefits. The Fact described the third-placed candidate as the casting voter.
Aggregating eight polls that asked Song's supporters for a second choice, the share naming Kim ran 69–85%. Applying the median of 77% gave a projected 52.19%. The actual result was 54.08%.
Full coverage of the race is in "Kim Min-seok elected Korea's ruling party leader with 54.08%."
5. Three common misunderstandings
"Ranking a likely loser first wastes your vote." Under this system it does not — reducing wasted votes is the design goal. When your first choice is eliminated, your second preference is counted instead. The exception: a ballot with nothing after the first preference is exhausted and stops there.
"A second preference counts less than a first." It does not. Once transferred, it is counted as one vote, indistinguishable from any other. This is also the standard criticism of the method — one voter's second-best is weighed equally against another voter's first choice.
"The published percentage is the level of real support." It is not. Reading 54.08% as "54% of members most wanted Kim" is wrong. Some portion of that total came from members whose first choice was Song Young-gil and who named Kim second.
6. What remains unconfirmed
First-preference shares were not published, so the size of the transfer that produced 54.08% cannot be calculated.
The measured transfer split is unknown. Pre-vote polling suggested 69–85%; the actual figure has not been released.
Rules on exhausted ballots were not obtained. How the party treats ballots left blank after the first preference, and how many there were, is unconfirmed.
Related coverage: "Kim Min-seok elected Korea's ruling party leader with 54.08%," "What a touring primary is," and "What a rights-holding party member is."
Sources
- Digital Times — Song Young-gil's second preferences decide the race if no first-round majority
- Kyunghyang Shinmun — Kim Min-seok elected with 54.08% under preferential voting
- MoneyToday — Kim and Jung trade the lead as attention turns to second preferences
- The Fact — The third-placed candidate as casting voter
- Namuwiki — Democratic Party of Korea, third regular national convention