The survey by the Centre for Sociological Studies (CIS) also showed a coalition of two conservative groups and a far-right party, which together won a majority of seats in the regional parliament of Andalusia last December, would not repeat the feat at national level on April 28th.
The Socialists would win 30.2 percent for 123-138 seats in the 350-seat parliament, below the 176-seat majority but far ahead of its nearest rival, the conservative Popular Party (PP), which would net 66-76 seats with 17.2 percent.
The poll shows the Socialists could team up with far-left coalition Unidos Podemos, set for some 30 seats, and a handful of smaller regional parties to govern without the help of Catalan separatist parties.
New poll just out by #CIS: Socialists would win big and may not need Catalan secessionist parties to form a ruling coalition (Podemos and the Basques nationalists may be enough).
Caveat: CIS' credibility has been called into question repeatedly. pic.twitter.com/CeZFg9aHl5
— Diego Torres (@jdiegotorres) April 9, 2019
Prime Minister Pedro Sanchez called the snap polls after Catalan separatists joined forces with the PP and conservative Ciudadanos to reject his minority government's 2019 budget proposal.
The Catalan parties helped bring Sanchez to power last June when he ousted PP prime minister Mariano Rajoy in a no-confidence vote but they later withdrew support over Madrid's opposition to an independence referendum for the region.
— M. M. Novau ? (@MmNovau) April 10, 2019
Ciudadanos would score 13.6 percent for 42-51 seats, making it another potential partner for the Socialists.
But Ciudadanos leader Albert Rivera has vowed he would not allow Sanchez to form another government over his willingness to negotiate with Catalan separatist parties.
Far-right party Vox has 11.9 percent support, giving it 29-37 seats as it looks to build on its December showing in Andalusia, a former Socialist stronghold.
A high number of voters, 41.6 percent, said they are still undecided, according to the poll of 16,000 voters March 1st-18th.