The Center for Sociological Research published its May barometer on Friday, giving the PSOE 36.2% voting intention and the PP 24.9%. The survey was conducted between 4 and 18 May, before recent corruption scandals.
The CIS study, led by José Félix Tezanos, shows a slight reduction in the socialist lead compared with the previous month. Vox rises to 16.2%, while Sumar obtains 5.7% and Podemos 2.5%.
The fieldwork coincided with the Andalusian election campaign and does not include the impact of the indictment of José Luis Rodríguez Zapatero, made public on 19 May, or other later investigations.
The barometer also asks about the national priority principle agreed by PP and Vox in Extremadura and Aragón. 52.2% of respondents reject it and 43.9% consider it compatible with the Constitution.