Prior to his time in office, Tomares had been dominated by the Spanish Socialist Workers' Party (PSOE).

[5] The two parties did not form a coalition and Sanz became mayor in a minority government, with Vox warning him that he would need their support to pass a budget.

[6] In June 2024, disputes over the budget led to a vote of confidence in Sanz, which was approved by the 14 PP members and rejected by the 17 others.

The result was a historic best for his party, which cut its deficit in the PSOE-dominated constituency by a quarter of a million votes and from 27 percentage points to 3.5.

[8] He lost his seat by a 2,500-vote margin in the April 2019 general election,[9] winning it back in November.