FILE PHOTO - People attend a rally called by Spain's emerging far-right party VOX, in Barcelona, Spain, March 30, 2019. REUTERS/Sergio Perez

MADRID (Reuters) - Spain’s ruling Socialists kept their lead but without the necessary majority before an April 28 election, according to a poll of polls compiled by newspaper El Pais, while support for the new far-right party Vox showed signs of waning.

Support for Vox slipped to 11 percent from 12.1 percent recorded in the paper’s last poll of polls released March 13. The Socialists would win 28.6 percent of the vote, El Pais said on Thursday, unchanged from the March survey.

The election could mark a watershed for Spain as a far-right party is forecast to get a foothold in the 350-seat national parliament for the first time in four decades.

Backing for the traditional conservative People’s Party (PP) rose slightly from previous surveys, with 20.2 percent of the vote, while market-friendly Ciudadanos slipped to 15.8 percent and the far-left Unidos Podemos held at 13.5 percent, the poll showed.

Spain was forced to repeat the December 2015 election in June 2016 after no single party succeeded in forming a government and repeated attempts to agree on a coalition failed.

Polls increasingly point to another hung parliament this time around.

The survey showed that a potential three-way, right-wing coalition between the PP, Ciudadanos and Vox would still not reach a majority in parliament. According to the survey, the PP would win 78 seats, Ciudadanos 54 and Vox 31, far short of the 176 seats needed to take the legislative house.

The Socialists would also struggle to reach a majority, however, with a two-way coalition with Unidos Podemos winning just 156 seats, forcing the government to find backing from an array of small, regional parties, including Catalan separatists.

The data represents an average of dozens of surveys carried out by different sources and weighted based on the size of the poll, the author of the poll and date, El Pais said.