As two candidates had entered the race, attention focused on Díaz as she refused to publicly disclose her intentions.
A party event on 11 February, allegedly intended as a vindication of the party's municipalism in Spain, became an improvised rally in support of Díaz, who had been invited by the event's organizer, Mayor of Vigo Abel Caballero.
During the event, attended by 2,500 party officers and supporters, Díaz strongly hinted at her candidacy by claiming that she had "strength, hope, excitement" and "loved winning", while also pointing that the PSOE had to recover its spirit to "win elections".
Amid rumours that she intended to make her announcement after the Day of Andalusia holiday on 28 February—in order to prevent eclipsing the holiday's institutional celebration—she responded that it was "a government event" and that she was not going to "talk about [her] party".
Díaz kept staging various acts as she was allegedly awaiting for the best time to make her announcement, seeking to prevent a possible succession struggle in Andalusia in the event she choose to step down as regional President and leader.
Finally on 12 March, several media outlets confirmed that Susana Díaz was poised to announce her bid during a large party rally in Madrid on 26 March, with the party structure under her influence quickly coalescing around her in order to prevent a Pedro Sánchez's win in the primary.
In a speech to a crowd of 5,000 supporters, Susana Díaz formally announced her candidacy on 26 March as planned, supported by former PSOE leaders Felipe González, José Luis Rodríguez Zapatero and Alfredo Pérez Rubalcaba, as well as party figures such as Eduardo Madina, Alfonso Guerra, Carme Chacón, José Bono, 11 former ministers, dozens of local mayors and deputation presidents and most of the regional PSOE premiers, who had already rallied around her throughout the previous months.

Concurrently, Pedro Sánchez increased his campaign agenda in Andalusia—which accounted for about a quarter of the party's membership—aware that Díaz's influence in the region and her expected strong primary showing there could dwarf his support in other communities.
As Díaz made her bid official, Sánchez proclaimed that there were only "two choices" for party members ahead of the May primaries: "the abstention [to Rajoy] or the [party's] grassroots", while proclaiming that the PSOE itself had to choose whether to be "in front of" or "below or next" to the PP.
Sánchez also clashed with the PSOE's managing committee on his campaign's financing: Sánchez's crowdfunding system—through which he had received €38,000 in the first way of its opening, far beyond expectations—was rejected by the later, as they accused Sánchez of not respecting laws on the financing of political parties.
The caretaker committee perceived that donations to candidates for an internal party process were also subject to the same legal regulations applied to parties, and that any resulting responsibilities derived from a lack of control of such payments could result in the party bearing ultimate responsibility.
As a result, the PSOE demanded all candidates to redirect their funding through a bank account under the party's ownership, something which was initially rejected by Sánchez—who also questioned the legality of such a move—to the party's outrage.
On 28 March, the Spanish Court of Auditors ruled in favour of the party's stance and required for Sánchez to respect the financing rules laid down by PSOE.
Sánchez reluctantly complied and subsequently shut down his crowdfunding.

Díaz and Sánchez's positions were seen as frontally antagonistic.
Whereas Díaz claimed herself to be the representative of "the true PSOE"—vindicating the party's legacy and the much criticized Socialist governments under Felipe González (1982–96) and Rodríguez Zapatero (2004–11)—, Sánchez was heavily critical of the party's direction ever since his resignation, calling himself "the candidate of the grassroots" and demanding a PSOE that was "autonomous, left-wing and credible".
Their personal grudge was so intense that PS
As two candidates had entered the race, attention focused on Díaz as she refused to publicly disclose her intentions. A party event on 11 February, allegedly intended as a vindication of the party's municipalism in Spain, became an improvised rally in support of Díaz, who had been invited by the event's organizer, Mayor of Vigo Abel Caballero. During the event, attended by 2,500 party officers and supporters, Díaz strongly hinted at her candidacy by claiming that she had "strength, hope, excitement" and "loved winning", while also pointing that the PSOE had to recover its spirit to "win elections". Amid rumours that she intended to make her announcement after the Day of Andalusia holiday on 28 February—in order to prevent eclipsing the holiday's institutional celebration—she responded that it was "a government event" and that she was not going to "talk about [her] party". Díaz kept staging various acts as she was allegedly awaiting for the best time to make her announcement, seeking to prevent a possible succession struggle in Andalusia in the event she choose to step down as regional President and leader. Finally on 12 March, several media outlets confirmed that Susana Díaz was poised to announce her bid during a large party rally in Madrid on 26 March, with the party structure under her influence quickly coalescing around her in order to prevent a Pedro Sánchez's win in the primary. In a speech to a crowd of 5,000 supporters, Susana Díaz formally announced her candidacy on 26 March as planned, supported by former PSOE leaders Felipe González, José Luis Rodríguez Zapatero and Alfredo Pérez Rubalcaba, as well as party figures such as Eduardo Madina, Alfonso Guerra, Carme Chacón, José Bono, 11 former ministers, dozens of local mayors and deputation presidents and most of the regional PSOE premiers, who had already rallied around her throughout the previous months.
Concurrently, Pedro Sánchez increased his campaign agenda in Andalusia—which accounted for about a quarter of the party's membership—aware that Díaz's influence in the region and her expected strong primary showing there could dwarf his support in other communities. As Díaz made her bid official, Sánchez proclaimed that there were only "two choices" for party members ahead of the May primaries: "the abstention [to Rajoy] or the [party's] grassroots", while proclaiming that the PSOE itself had to choose whether to be "in front of" or "below or next" to the PP. Sánchez also clashed with the PSOE's managing committee on his campaign's financing: Sánchez's crowdfunding system—through which he had received €38,000 in the first way of its opening, far beyond expectations—was rejected by the later, as they accused Sánchez of not respecting laws on the financing of political parties. The caretaker committee perceived that donations to candidates for an internal party process were also subject to the same legal regulations applied to parties, and that any resulting responsibilities derived from a lack of control of such payments could result in the party bearing ultimate responsibility. As a result, the PSOE demanded all candidates to redirect their funding through a bank account under the party's ownership, something which was initially rejected by Sánchez—who also questioned the legality of such a move—to the party's outrage. On 28 March, the Spanish Court of Auditors ruled in favour of the party's stance and required for Sánchez to respect the financing rules laid down by PSOE. Sánchez reluctantly complied and subsequently shut down his crowdfunding.
Díaz and Sánchez's positions were seen as frontally antagonistic. Whereas Díaz claimed herself to be the representative of "the true PSOE"—vindicating the party's legacy and the much criticized Socialist governments under Felipe González (1982–96) and Rodríguez Zapatero (2004–11)—, Sánchez was heavily critical of the party's direction ever since his resignation, calling himself "the candidate of the grassroots" and demanding a PSOE that was "autonomous, left-wing and credible". Their personal grudge was so intense that PS
2017 PSOE leadership election