Spain elects 350 members of Congress in 52 separate constituencies. Understanding those local contests is essential to understanding why a national polling lead does not translate directly into a parliamentary majority.
The province is the starting point
Each of the 50 provinces receives an initial allocation of two Congress seats. Ceuta and Melilla each elect one deputy. The remaining 248 seats are distributed among provinces according to population. The constituency allocations for the November election are set out in the annex to Royal Decree 806/2026.
This produces constituencies of different sizes. Winning a seat in a province with only a few deputies requires a different distribution of support from winning a seat in a large province. National percentages conceal those differences.
How D’Hondt allocates seats
Under Articles 162–164 of LOREG, lists below 3% of valid votes in a constituency are excluded from the allocation. The votes for each eligible list are divided by 1, 2, 3 and successive whole numbers. The largest quotients receive the available seats. Deputies are taken in the order in which candidates appear on the list. Ceuta and Melilla each return the candidate with the most votes.
The statutory 3% threshold is local, not national. Clearing it does not guarantee a seat: in a small constituency, a list may still have no quotient high enough to win one.
A worked example—not an election projection
Imagine a five-seat constituency with three eligible lists: A receives 50,000 votes, B 30,000 and C 20,000. The five largest quotients are 50,000 (A), 30,000 (B), 25,000 (A), 20,000 (C) and approximately 16,667 (A). The allocation is A three seats, B one and C one. These are invented numbers used only to explain the calculation.
The example also explains why applying D’Hondt once to a national poll would be wrong. The real allocation is repeated in each constituency using its own votes and number of seats.
The 176-seat threshold and investiture
An absolute majority of a 350-member Congress is 176. Under Article 99 of the Constitution, the first investiture vote requires an absolute majority. If it fails, another vote follows 48 hours later and requires a simple majority. Abstentions therefore matter. A combination of parties reaching 176 seats is an arithmetic possibility, not proof that they have agreed to govern together.
The Senate follows different rules
The 2026 election chooses 209 senators directly. Voters select individual Senate candidates, with limits that depend on the constituency. In provincial constituencies electing four senators, a voter may choose up to three candidates. The highest-polling candidates fill the available seats. Island constituencies and Ceuta and Melilla have different allocations and voting limits. Autonomous-community appointees are separate from these directly elected senators.
What this means for polling coverage
Votendi keeps vote estimates, pollster seat projections and official results separate. A survey’s published seat model should carry the pollster’s name and date; it should never be presented as a Votendi forecast. The 40dB. survey of 7–8 October illustrates the distinction between reported voting intention and a pollster’s own seat estimates.
Sources checked on 29 October 2026: LOREG, the Spanish Constitution and the official 2026 election decree.
Continue with the Spain election hub and polling tracker and the 2026 election guide.
