The unexpectedly good result for Sánchez's PSOE and the underperformance of the PP-led right-wing bloc triggered speculation over the future of PP leader Alberto Núñez Feijóo.

Following weeks of political tensions, which saw Sánchez accepting an amnesty law for Catalan separatist politicians convicted or investigated for events related to the 2017–2018 Spanish constitutional crisis and the 2019–2020 Catalan protests, he was able to secure the support of Sumar, ERC, Junts, EH Bildu, PNV, BNG and CCa to be re-elected as prime minister by an absolute majority on 16 November 2023; the first time since 2011 that a repeat election was not needed, as well as the first time since that date that a candidate was elected in the first ballot of investiture.

The candidate nominate [sic] in accordance with the provisions of the foregoing paragraph shall submit to the Congress of Deputies the political programme of the Government that he intends to form and shall seek the confidence of the Houses.3.

[15][16] PSOE promptly rejected this request as impossible after "years of insults", and described it as an attempt by Feijóo to "cover up his failure" by pretending he could command sufficient support for his investiture.

[29] Former Madrilenian president Esperanza Aguirre said during an interview that the election result was attributable to Feijóo's strategy of "seeking to reach out to the PSOE rather than governing with Vox", and commented that Ayuso was the future of the party and of Spain.

The PP then U-turned on its previous hardline stance towards Junts on 29 July, expressing willingness to engage in talks with Puigdemont's party "within the Constitution's framework" in order to invest Feijóo as prime minister,[38][39] though this was later ruled out by Gamarra.

[40] That same day, Puigdemont tweeted that his party would not be convinced by "political blackmail", and saw only three possibilities out of the deadlock: Junts voting in favour of Sánchez, the PSOE allowing Feijóo's investiture, or a repeat election.

[44][45] Sánchez wrote back the same day noting that, in a parliamentary democracy, it is whoever secures the most support in Congress, and not the most votes, who is entitled to govern, and reminding Feijóo of the multiple PP–Vox agreements reached in previous years throughout Spain in which the PP did not finish in first place.

CCa, until then considered as a likely Feijóo ally, expressed its willingness to negotiate an investiture agreement with Sánchez, on the grounds that, while it rejected any government that included either Sumar or Vox, it felt closer to Yolanda Díaz's party than to Santiago Abascal's.

[77] Vox leader Santiago Abascal described the results as "real shame" and said he would demand an explanation from the PP, or else he would re-evaluate his party's support for any investiture attempt by Feijóo.

[84] Feijóo's intentions were unchanged by his recent parliamentary setback, despite calls from some factions within his party asking him to "leave the fiction" of insisting that he had the required support for his investiture.

[102][103] In a meeting with Sánchez on 30 August, Feijóo asked the PSOE to facilitate his investiture for a 15-ministry government that would pass six major state pacts in a legislature to last a maximum of two years, with a new election scheduled for 2025.

Following this meeting, the PP shifted towards accusing Pedro Sánchez of negotiating with Junts to grant its request of an amnesty law for all those convicted or prosecuted for the events surrounding the 2017 Catalan independence referendum and the 2017–2018 Spanish constitutional crisis.

[125][126] Simultaneously, a reform of the Congress internal regulations was proposed to allow for the use of co-official languages (Catalan, Basque and Galician, as well as any other "that has official status in any autonomous community in accordance with the Constitution and the corresponding Statute of Autonomy") in parliamentary debates, the fulfillment of a pledge from the PSOE to ERC and Junts in exchange for their support for Armengol's candidacy for the post of speaker.

[131] In what was regarded by the media as an attempt to reaffirm his leadership within the PP, Feijóo used his speech to attack Sánchez and the amnesty proposal tabled by Catalan pro-independence parties.

[136][137] Following Feijóo's defeat, King Felipe VI summoned all parties to a new round of talks on 2 and 3 October, after which he nominated Pedro Sánchez as the next candidate to attempt the investiture.

[145] On 24 October, Sánchez and Sumar leader Yolanda Díaz signed an agreement to form a new coalition government, which included pledges to reduce the working week, raise the minimum wage and increase parental leave.

[146] In an attempt to accelerate talks with PNV, EH Bildu and BNG, as well as with Junts and ERC,[147] Sánchez announced on 28 October that he had agreed to back an amnesty law, to include all those involved in the controversial 2017 Catalan independence referendum and the subsequent constitutional crisis.

[157] Disagreements over the wording and scope of the proposed amnesty law were reported to be the main obstacles to an agreement,[158] in particular whether it would apply to those prosecuted or convicted for corruption scandals (such as the family of Jordi Pujol or Junts president Laura Borràs), which the PSOE opposed.

[170] Following Sánchez's announcement of an amnesty law on 28 October, the PP described it as an "attack on democracy" and demanded a re-run of the election,[171] while adopting a strategy of street protests against the incoming government.

[179] That same day, eight conservative-leaning members of the General Council of the Judiciary (CGPJ)—in a deep constitutional crisis over a lack of renewal since 2018—called for an extraordinary plenary session to approve an institutional declaration against the amnesty.

[182] The progressive Judges for Democracy association criticized the actions of the CGPJ, due to its interim nature, the perceived overreach of its functions, and the fact that the contents of the amnesty law were still unknown.

[186][187] That same day, National Court judge Manuel García-Castellón indicted Puigdemont and ERC secretary-general Marta Rovira for crimes of terrorism during the 2019–2020 Catalan protests, specifically during the riots involving the Democratic Tsunami and the CDRs, in a move seen as interference in the investiture negotiations.

[193] The amnesty was supported by the Financial Times which, while viewing it as an "expedient policy" by a Pedro Sánchez who "would not go down this path if his job were not on the line", also regarded it as "a gamble worth taking" to ease tensions in Catalan society following the 2017 events.

[194] On 8 November, European Commissioner for Justice Didier Reynders sent a letter to the Spanish government requesting more information "on the personal, material and temporal scope" of the planned amnesty law, as it had become "an issue of considerable importance in public debate" seeing how the European Commission had been contacted about it "among others, by a large number of citizens"; the Spanish government replied that legislative initiative belonged to Congress, not the executive branch, which was still in acting capacity and was legally barred from tabling any bill.

[196][197] Starting on 3 November 2023, street protests were organized outside PSOE offices around Spain, with the main focus on the party's headquarters on Calle de Ferraz in Madrid.

[199][200][201] The largest of the protests, on 7 November, was attended by 7,000 people; the ensuing riots saw 29 police officers wounded,[202][203] as well as an attempt to force entry into the heavily fortified Congress of Deputies.

[210] Basque Lehendakari Iñigo Urkullu, a member of the PNV, demanded that Feijóo "call off his protests against the amnesty law", as they were "serving as an excuse to generate hatred, resentment and violence".

[211] Following the announcement of the PSOE–Junts agreement, Madrid premier Isabel Díaz Ayuso controversially stated during an interview on Antena 3 that Spain was now "entering a dictatorship", and that she was counting on the King, the security forces and the army to "save the situation".

PSOE and PSC members approved of the renewal of the alliance with Sumar and the support "of other political formations to achieve the required majority" by 88% and 87% respectively, in votes held between 30 October and 4 November.