By Belén Carreño and Jessica Jones

MADRID Spain's Socialists may have lost power in the key regions of Valencia and Aragon in Sunday’s local elections, according to a poll by state broadcaster TVE, showing electoral vulnerability ahead of end-of-year general election.

Final figures will be released later on Sunday and tight numbers show that some of the other ten regions, most of them currently run by the governing Socialist Party (PSOE), and towns could swing with a narrow margin.

The poll predicts gains for the conservative People's Party (PP), which if replicated later in the year could unseat the current left-wing coalition.

But the PP will likely have to rely on the far-right Vox to form governments in Valencia and Aragon, in a possible precursor to a right-wing coalition government after the general election.

The poll showed few clear majorities, except in the region of Madrid, where regional president Isabel Diaz Ayuso of the PP likely won re-election with an absolute majority.

If confirmed, the defeat for the socialists in the Valencia region, with a population of almost five million, would represent a major setback for the PSOE.

Over 35 million people were eligible to vote and the turnout as of 6 p.m. (1600 GMT) was 51.48%, higher than the 49.93% at the same time in 2019's local elections, despite rain and bad weather.

Campaigning had been marked by several controversies, from allegations of voter fraud in small towns to an unprecedented case of kidnapping.

The elections also mark the beginning of a return to a two-party system dominated by the PSOE and PP after a decade of greater involvement for smaller parties such as the left-wing Podemos, the government's junior partner, and centrist Ciudadanos.

(Reporting by Jessica Jones and Belen Carreno; Writing by Jessica Jones; Editing by Hugh Lawson)