The deal and its name

The Spanish Socialists (PSOE) and the Frente Amplio alliance agreed to stand under one ballot in the Senate election of 29 November, closing the deal in the final hours before coalitions had to be registered at 23:59 on Friday, 16 October. The pact became public after 22:00. The joint coalition will be called 'Senado de Progreso' and includes the PSOE, Izquierda Unida (IU), Movimiento Sumar, Compromís, Más Madrid, Chunta Aragonesista and Batzarre. These parties will not compete against one another for the seats at stake and will instead field joint lists in the constituencies covered by the pact. Of the 208 senators chosen directly by voters, El Mundo notes that another 58 are designated by regional parliaments.

Scope, and where sources differ

The sources do not agree on how many provinces the joint lists cover. El Mundo reports 48 provinces, all except the four Catalan ones, while El Periódico puts the figure at 46, also excluding Catalonia. El Periódico says the initial plan covered about 20 provinces before the parties widened it in the final hours. A parallel pact between the PSC and the Comuns did not materialise, although El Periódico expects the socialists to win in the four Catalan provinces, which it says secures a left majority there. El País reports that the deal also builds on an existing PSOE and Més-Izquierda Unida-Sumar agreement in the Balearic Islands, and says it will not apply in every constituency.

Why the left is uniting

Socialist sources cited by elDiario.es say the PP has used the Senate in a 'spurious' way over the past three years, including blocking the renewal of the Constitutional Court through its absolute majority. El Periódico reports that socialist sources hope to 'defeat the right and the far right' in the upper house, and expect a mobilising effect ahead of the Congress vote. El Mundo points to the 2023 result, in which the PP won 120 of the 208 directly elected seats, and estimates that a single PSOE and Sumar list that year would have given the left a majority in the chamber during this legislature.

Talks and the Podemos split

Negotiations began about a week before the deal, when Ferraz opened the door to the alliance, and the parties met the previous Sunday. Rebeca Torró, the PSOE's organisation secretary, led the talks for the socialists, according to El Periódico. Earlier on Friday, La Vanguardia reported that the single Senate list had been shelved over territorial differences, with the Frente Amplio's Congress talks absorbing most of the effort. That report predated the late agreement. Podemos is not part of the pact, although El País says it could still propose names with the backing of the other forces. On Wednesday, 14 October, Podemos regional leaders contacted IU's regional coordinators to explore pacts in ten regions, bypassing the federal leadership of Antonio Maíllo. Maíllo dismissed the approach on TVE:

“IU will negotiate from the Frente Amplio because it is a serious, honest and loyal organisation.”

What comes next

The PSOE's Federal Committee meets in Madrid on Saturday, 17 October, to ratify its lists for the 29 November vote and Pedro Sánchez as its candidate for the Presidency, according to elDiario.es. The negotiators have not yet discussed candidate names, because Friday's deadline applied only to coalitions and not to lists. A platform called 'Senadoras y senadores por la Democracia', presented in the week of 5 October 2026, has thousands of signatories and presses left parties for joint lists, and the Fundación Pedro Zerolo, close to the PSOE, has joined it. The vote itself takes place on 29 November.