Pedro Sanchez is heading for victory and the Partido Popular (PP) and Vox would fall short of a majority, according to the latest state-funded election poll.
But the CIS’s projection has reopened questions about its reliability, with critics pointing to its record of overestimating the left.
Meanwhile, its performance in the 2023 general offers a more complicated picture, including some accurate predictions alongside big misses.
The latest survey, released yesterday, gives the PSOE 33.3% of the vote, against 25.5% for the PP and 18.4% for Vox.
Even at the top of their projected seat ranges, the two right-wing parties would miss an outright majority.
The findings differ sharply from private polling, according to a comparison published by right-leaning newspaper El Español.
Much of the backlash concerns the survey’s composition. El Español reports that 37.4% of respondents said they voted PSOE in 2023, considerably above the party’s actual share of the total electorate.
It argues that Socialist voters are therefore overrepresented and PP voters underrepresented.
Meanwhile, myth-busting publication Maldita cites an El Pais analysis published in June 2024. It found that the CIS had overestimated the combined left-wing vote in 41 of 42 elections since Jose Felix Tezanos became president of the company in 2018.
In the 2024 European election, it estimated 42.4% for the PSOE, Sumar and Podemos combined. They ultimately received 38.1%.
Tezanos’s political background has also intensified the controversy, as he previously held a position in the PSOE leadership before taking charge of the CIS, whose president is appointed by the government.
Criticism has extended beyond the PP and Vox to several other parliamentary parties.
Yet claims that the CIS invariably gets everything wrong also overlook its 2023 performance.
Fact-checker Newtral found that its final poll came closest to the PSOE’s eventual vote share, predicting 32.2% against a final result of 31.7%.
It also correctly envisaged the PP and Vox falling short of a majority, although several other pollsters identified that possibility too.
The CIS nevertheless put the PSOE ahead of the PP, getting the winner wrong. Newtral ranked it fourth for accuracy across the four largest pollsters, behind 40dB., Cluster17 and ElectoPanel.
The fact-checker therefore rated minister Felix Bolaños’s claim that the CIS was the only pollster to get 2023 right as misleading.
The timing of the latest survey is also significant, as although it was released on November 12, the 45,074 interviews were conducted between October 7 and 30.
Most preceded the Urda rail disaster on October 28, limiting what the poll can reveal about its political aftermath.
It means the results, particularly the eight-point lead, should be treated cautiously, particularly considering its past tendency to overestimate the left.
