The battle for the Senate has opened a new front in the pre-campaign for the general elections on November 29. The PSOE and Frente Amplio have reached an agreement to present joint candidacies under the name "Senado de Progreso," while Vox is considering renouncing to run in certain provinces to favor the candidates of the Partido Popular. Two different strategies that respond to the same peculiarity of the electoral system: the concentration of the vote can considerably modify the distribution of seats in the Upper House.
The decision that Santiago Abascal is considering, reported this Saturday by El País, would represent a change from the strategy that Vox has maintained in previous elections. The party is contemplating not presenting lists for the Senate in those constituencies where it believes its candidates have little chance of obtaining representation and asking its voters to support the popular candidates.
The proposal is not yet approved. The general secretary of Vox, Ignacio Garriga, has warned that the party will have to make "difficult decisions," while sources from the party indicate that all options remain open pending a statement from the National Executive Committee.
For its part, the PSOE and its partners have already finalized the electoral agreement, although they still need to complete the distribution of positions and the designation of candidates. The alliance covers 47 constituencies, according to the balance communicated by its promoters, with specific formulas in certain territories and exceptions like Catalonia.
Vox considers withdrawing from some provinces to concentrate the vote on the PP
The possibility that Vox is examining consists of not presenting its own candidates for the Senate in certain constituencies and requesting the vote for the candidates of the Partido Popular. This formula would allow coordinating the electoral behavior of both electorates without the need to form a formal coalition.
The deadline to register coalitions ended at midnight on Friday, October 16, so PP and Vox can no longer formalize an electoral alliance equivalent to that reached by PSOE and Frente Amplio. However, the presentation of candidacies will take place between October 21 and 26, which leaves room to decide where each party will run.
The other alternative would be to incorporate candidates from Vox into the lists of the PP, although, according to the information published by El País, this option is considered less likely. In any case, it has not been communicated which provinces could be affected nor if there is a closed agreement between the leaderships of both parties.
Abascal has reacted to the left's pact with a message directed at his voters in which he assures that he will act "with a broad perspective" and will do "what is necessary" to prevent Spain from depending on Pedro Sánchez. The leader has not expressly confirmed the withdrawal of candidacies, but his words leave open the possibility of adopting a different strategy than the one followed so far.
The decision also presents difficulties for Vox. Renouncing to run for the Senate would mean asking its voters to support candidates from another party, with the risk of strengthening the PP in a call in which both formations compete separately for Congress.
Moreover, the relationship between the popular and Vox presents territorial particularities that could complicate coordination. In Ceuta, for example, the discrepancies between Vox and the president of the autonomous city, the popular Juan Jesús Vivas, have marked the relations between both organizations.
The precedent of 2023: Vox was left without directly elected senators
The reflection of Vox has an immediate precedent in the general elections of July 2023. Although its candidates received a considerable volume of support, the party did not achieve any senator by direct election.
According to the data collected by El País, the best-placed candidates of Vox totaled more than 2.7 million votes, without that support translating into representation in the constituencies where they ran.
The situation did not prevent the Popular Party from obtaining an absolute majority in the Senate. However, the agreement now reached by PSOE and Frente Amplio introduces a different variable, allowing left-wing candidates to concentrate support that was previously distributed among several formations.
The withdrawal of Vox in some provinces would not guarantee that all its voters would vote for the PP. The effectiveness of that strategy would depend on how many voters followed the recommendation and how they distributed their votes among the different candidates.
The price of unity: PSOE and Frente Amplio share the candidacies
While PP and Vox study their options, the left has surpassed the first phase of the negotiation. The agreement called "Senado de Progreso" brings together PSOE with Izquierda Unida, Movimiento Sumar, Más Madrid, and various territorial organizations, including Compromís, Chunta Aragonesista, Batzarre, and Més.
The pact implies sharing candidacies in a large part of the national territory but forces the participating parties to negotiate which candidates will occupy the most prominent positions. The electoral unity thus has a direct consequence on the distribution of positions between the socialists and their partners.
In the peninsular provinces, each voter can vote for a maximum of three candidates, although four senators are elected. Therefore, the parties place special importance on the composition of the slates they present to the voters.
PSOE maintains a predominant position in the known territorial agreements, although it reserves spaces for the organizations of Frente Amplio. The distribution is not identical in all provinces and depends on the negotiations between the territorial leaderships.
Aragón: two socialist positions and one for CHA or IU
Aragón offers one of the clearest examples of the distribution. PSOE will occupy the first and third positions of the candidacies for the Senate for Zaragoza, Huesca, and Teruel, while the second will be reserved for its partners.
Chunta Aragonesista will designate the candidates who will occupy that position in Zaragoza and Teruel, while Izquierda Unida will do so in Huesca.
In this way, the socialists will have six of the nine main positions in the three Aragonese provinces, CHA will have two, and IU one. The agreement allows organizations of the alternative left to participate in a shared candidacy with PSOE without renouncing their own lists for Congress.
Galicia and Comunidad Valenciana: the territorial concessions
In Galicia, the agreement extends to the four provinces. The socialists will lead the candidacies and reserve the second positions for representatives of Frente Amplio, although all the names of the candidates from the alternative left still need to be specified.
In the Comunidad Valenciana, the PSOE has also agreed to share the candidacies with Compromís-Front Valencià and its allies. The agreement stipulates that the socialists will head the lists for Valencia, Alicante, and Castellón, while the positions reserved for the alternative left will be distributed among their territorial organizations.
The known distribution assigns to Compromís the positions corresponding to Valencia and Alicante and to Esquerra Unida del País Valencià that of Castellón. The socialists will retain two of the three main spaces in each province.
These agreements allow for the identification of some of the concessions made by the PSOE, but there is still no definitive list of all the candidacies that would allow for calculating how many positions will correspond to each organization across Spain.
The territorial distribution of the joint candidacies
The following table collects the agreements known up to this Saturday, October 17. The positions still pending confirmation are kept separate from the already assigned positions.
| Province | PSOE | Partner |
|---|---|---|
| Zaragoza | 1st and 3rd | CHA (2nd) |
| Huesca | 1st and 3rd | IU (2nd) |
| Teruel | 1st and 3rd | CHA (2nd) |
| A Coruña | 1st | Frente Amplio (2nd) |
| Lugo | 1st | Frente Amplio (2nd) |
| Ourense | 1st | Frente Amplio (2nd) |
| Pontevedra | 1st | Frente Amplio (2nd) |
| Valencia | 2 positions | Compromís (1) |
| Alicante | 2 positions | Compromís (1) |
| Castellón | 2 positions | EUPV (1) |
Source: territorial agreements known until October 17, 2026. The final distribution of candidates remains pending.
The candidates who may be left out due to the distribution
The negotiation will also have consequences for the leaders who aspired to be part of the candidacies for the Senate. The concession of positions to partners reduces the number of available positions for socialist candidates, while the organizations of Frente Amplio must distribute among themselves the spaces they have obtained.
In Aragón, for example, the distribution leaves two second positions for CHA and one for IU. In the Comunidad Valenciana, Compromís will have representation in two provinces and EUPV in one.
For now, there is not enough information to generally identify which leaders have lost their position as a result of the agreement. That comparison can only be completed when the final lists are known and contrasted with the proposals that the organizations had initially prepared.
The three-to-one rule that explains the electoral movements
The strategy of both blocs responds to the limited voting system that regulates the elections to the Senate. In the peninsular provinces, four senators are elected, but each voter can select a maximum of three candidates.
The seats correspond to the four people who receive the most votes. When voters predominantly support the three candidates from the same candidacy, they usually obtain three seats, while the fourth goes to another party.
This mechanism explains the usual distribution of three to one, although it is not an automatic rule. Citizens can combine candidates from different parties, and the order of the candidates depends on the individual votes they receive.
The concentration of candidacies can modify the distribution of seats even when the general distribution of support among the parties barely varies. For that reason, PSOE and Frente Amplio have opted to share ballots, and Vox is considering a partial withdrawal that would allow concentrating support on popular candidates.
A decisive majority for laws and constitutional bodies
Control of the Senate has consequences that go beyond the number of elected representatives. Although Congress retains the predominant position in the approval of ordinary laws, the Upper House can introduce amendments and veto legislative projects, forcing deputies to vote again.
The Senate also participates in the renewal of constitutional bodies. The appointment of the four magistrates of the Constitutional Court that it is responsible for proposing requires a three-fifths majority, just like certain appointments of the General Council of the Judiciary.
In addition, the Chamber has specific competencies in the application of Article 155 of the Constitution, whose authorization requires an absolute majority.
The difference between controlling the absolute majority and reaching three-fifths is, therefore, relevant for the institutional negotiations of the next legislature.
October 26, the next decisive date
With the deadline for coalition registration concluded, the parties must resolve their decisions in the coming days. Between October 21 and 26, the electoral candidacies will be presented, which will allow knowing both the definitive distribution of positions in the Senate of Progress and the territorial strategy of Vox.
In the case of the left, it will remain to be determined how many candidates each party ultimately contributes and which leaders will occupy the most prominent positions. In the case of the right, the main unknown is whether Vox maintains its own candidacies in all constituencies or renounces some to request votes in favor of the PP.
The negotiation of the Senate has thus acquired a different dynamic from that of the Congress. While in the Lower House PSOE, Frente Amplio, and Podemos will compete with different electoral formulas, in the Upper House the socialists have reached a unity agreement and Vox is studying indirect coordination with the PP.
The decisions made before October 26 will determine what options voters will find on the Senate ballots on November 29. The result will then depend on the individual votes received by the candidates, in a competition where alliances and renunciations can have relevant consequences for the composition of the Chamber.