In a few weeks before the elections on November 29, Vox can celebrate that it is the party that grows the most, according to all polls. However, what is a reason for celebration for Abascal's party may operate in an opposite sense for a hypothetical parliamentary majority of PP and Vox.
In fact, the provincial distribution of support and the particularities of the Spanish electoral system can cause the competition between both candidacies to modify the distribution in favor of other forces.
The issue takes on special importance in provinces that elect few deputies, where small variations in the results can determine who obtains the last representative. The D'Hondt formula, applied independently in each constituency, does not sum the votes of parties that may be part of the same parliamentary block, but rather assigns seats based on the results of each candidacy.
Vox grows while the PP declines in the polls
The latest barometer from 40dB published on October 5 reflects the evolution of the vote for both parties. The PP obtains an estimated vote of 31.6%, eight tenths less than in September, while Vox reaches 18.4%, six tenths more. The PSOE stands at 27.4%, after declining two tenths compared to the previous survey.
The survey reflects that 13.5% of those who voted for the PP in the general elections of 2023 would now choose Vox, while only 1.6% of former voters of Santiago Abascal would lean towards the popular party.
Despite Vox's growth at the expense of the popular party, the sum of both formations reaches 50% of the voting intention. The possible benefit for the PSOE, therefore, does not directly stem from the national percentages, but from how the votes are distributed among the different provinces.
Small provinces, decisive for the last deputy
The Congress is elected through 52 constituencies, corresponding to the 50 provinces and the autonomous cities of Ceuta and Melilla. Each province has a minimum of two representatives, to which other deputies are added based on its population, while Ceuta and Melilla elect one each.
The distribution is carried out through the D'Hondt system, which divides the votes obtained by each candidacy by a series of consecutive numbers and allocates the seats to the highest quotients. This procedure can cause the distribution of deputies to vary even if the sum of votes of two parties remains practically the same, especially when the last seat is decided by narrow differences.
The competition between PP and Vox takes on special relevance in constituencies such as Ávila, Segovia, Soria, Teruel, Cuenca, Guadalajara, Zamora, or Palencia, where few deputies are distributed and each seat represents a high proportion of provincial representation. In these territories, the D'Hondt system makes the distance between the votes of the different candidacies particularly important, although the growth of Vox does not necessarily imply that PP loses a deputy or that PSOE benefits.
Ávila is a particularly illustrative example. In the 2019 elections, its three deputies were distributed among PP, PSOE, and Vox, with one for each party. Four years later, PP obtained two representatives and PSOE retained one, while Vox was left without a seat despite gathering 15.4% of the votes. The precedent shows how changes in support for the two right-wing formations can modify their representation in a province with few deputies.
It is also worth observing constituencies of four or five seats, such as Burgos, Salamanca, León, La Rioja, Toledo, or Ciudad Real, where the entry of a third candidacy can alter the distribution among the main parties.
The possible effect of this competition on the provincial distribution has been incorporated into the electoral debate, although there is still no sufficiently detailed projection that allows for the identification of constituencies where PSOE could benefit from a transfer of support between PP and Vox.
PSOE also needs to concentrate support to its left
The competition between PP and Vox coincides with another phenomenon that can condition the composition of the next Congress. The fragmentation of the space to the left of PSOE, with Sumar and Podemos running as differentiated options if they do not reach an agreement, can also hinder the conversion of votes into seats.
The 40dB barometer places Sumar at 5.6% of estimated votes and Podemos at 2.7%, percentages that do not allow determining by themselves how many deputies each party would obtain. In small provinces, where the number of representatives is reduced, the territorial concentration of support is especially important.
In this way, the PSOE may face two simultaneous effects of the electoral system, one derived from the competition between PP and Vox and another related to the distribution of votes among progressive candidacies. Both influence the distribution of seats, although not necessarily in the same direction.