Spain's Prime Minister Pedro Sanchez arrives at an extraordinary European Union leaders summit to discuss Brexit, in Brussels, Belgium April 10, 2019. REUTERS/Susana Vera

MADRID (Reuters) - Spain’s Socialists held the lead in voting intentions ahead of the April 28 election, a GAD3 poll for the ABC newspaper showed on Thursday, but they were seen short of a parliamentary majority even with backing from far-left allies Podemos.

Voting intention surveys have illustrated how deeply Spain’s political system is torn between five parties as the country heads in to a bitterly fought parliamentary election.

Prime Minister Pedro Sanchez’s Socialists would win between 135 and 137 seats, the poll of 2,000 people taken on April 8-9 showed, short of a majority in the 350-seat parliament and slightly less than previously reported April 8.

Podemos would take 29-30 seats, the poll showed, placing a potential left-wing alliance below the 176 seats necessary for a overall majority in the lower house and highlighting the razor-thin margins ahead of the election.

The poll comes just two days after an official survey from the state-run Centre for Sociological Studies (CIS) showed a Socialists-Podemos coalition could win the necessary seats.

While surveys teeter between the possibility of a right-wing or left-wing coalition winning a majority, the CIS poll noted that almost 42 percent of those surveyed had still to decide, adding to uncertainty ahead of election night.

According to the GAD3 poll, the conservative People’s Party (PP) would take 85-91 seats, up slightly from this pollster’s previous survey, while market friendly Ciudadanos may take 43-46 seats, and far-right Vox, 25-29 seats, also up from the previous poll.

The GAD3 poll showed a three-way coalition between the conservatives would still fall short of a parliamentary majority in the best of cases.