Contingent Election

Overview#

The US 12th Amendment fallback when no presidential candidate reaches an Electoral College majority. The House elects the President; the Senate elects the Vice President. Source: src/lib/elections/contingentElection.ts10d ago.

This is not a raw 435-member roll call. Each state delegation casts one combined vote (26 states needed to win). Representatives only decide how their state's single delegation vote is cast. DC has electoral votes but no voting House delegation and is excluded from the House ballot. The Senate elects the VP on a one-vote-per-senator basis.

Eligibility#

resolveContingentElection throws if the presidential candidate list includes anyone outside the expected top 3 (assertPresidentCandidatesEligible).

Thresholds#

If the Vice President ballot has exactly one eligible candidate, that candidate wins outright with no Senate vote. With two or more, the Senate votes.

Voter Preference Model#

Each House member and senator scores every eligible candidate:

score = (party match ? PARTY_MATCH_BONUS : 0) - ideologyDistance
ideologyDistance = |voter.economic - candidate.economic| + |voter.social - candidate.social|

PARTY_MATCH_BONUS = 35, kept modest so ideology distance (roughly 0-20) can still swing close races. pickPreferredCandidate returns the candidate with the best score; a voter-level tie is broken deterministically by hashing tieSeed with the sorted tied candidate ids (sha256, first byte mod tie-count).

NPP bloc officials can be aggregated into a single voter with a weight field (default 1) instead of one row per official.

House Delegation Vote#

calculateHouseDelegationVote sums each delegation's weighted picks per candidate. A delegation votes for the candidate with the strict majority of its own weighted picks; a delegation-level tie means that state abstains (null). DC always abstains. A delegation with zero eligible voters or zero eligible candidates also abstains.

calculateHouseDelegationVotes runs this across all delegations and returns per-state votes plus a candidate → delegation-count total (one point per state, not per representative).

Senate VP Vote#

calculateSenateVpVotes is a flat one-senator-one-vote tally over the eligible VP candidates using the same preference model, keyed with tieSeed:senate:{senatorId}.

Winner Resolution#

resolveWinnerFromTotals (shared by House and Senate):

1. Rank candidates by vote total, ties broken by id.
2. If the leader's total meets the chamber threshold (26 states / 51 senators), that candidate wins outright.
3. Otherwise deadlock: among the tied leaders, a deterministic hash of electionId:deadlock:{context}:{sortedIds} picks the winner (sha256, first byte mod tie-count). deadlockBreakerUsed = true and a deadlockBreakerReason string is recorded.
4. If the ballot produced no votes at all (every voter unable to pick, or an empty chamber), resolveContingentEvFallback breaks the tie by original electoral-vote count instead of chamber votes, with its own deterministic hash keyed electionId:ev-fallback:{context}:{sortedIds}.

Result Shape#

ContingentElectionResult:

Determinism#

All random-seeming choices (voter-level ties, delegation-level ties, chamber-level deadlocks, and the EV fallback) are sha256-hashed off electionId plus a context string, never Math.random(). The same election always resolves the same way if replayed.