MADRID (Reuters) - Spain's conservative People's Party (PP) and newcomers Ciudadanos could claim a small majority in parliament if a new election is called after months of failed coalition talks, according to a poll published on Monday.
The poll, by Sigma Dos for conservative newspaper El Mundo, was the first to show a possible alliance between the PP - which runs the caretaker government in the political deadlock following December's general election - and the market-friendly Ciudadanos (Citizens) party.
A Metroscopia poll for the left-leaning daily El Pais on Sunday also showed the PP and Ciudadanos gaining ground, but found no possible two-way majority except for a grand coalition of the PP and the Socialists, an option that has been widely rejected.
Spain's main parties on the right and left have been struggling to assemble a group large enough to form a government, but wide ideological differences and months of failed talks mean a deal is looking increasingly unlikely.
If there is no agreement by May 2, new elections will be held, probably at the end of June.
The El Mundo survey said the PP would take 128 seats and Ciudadanos, which has shown willingness to form a coalition with acting Prime Minister Mariano Rajoy's party, would take 52 seats.
That would be enough to top the 176 seats needed to take an absolute majority in parliament and form the next government.
The poll surveyed 800 people at the end of March. But with a margin of error of +/-3.5 percent, the poll suggests Spain may still end up with the four-way impasse echoed in other polls.
A coalition plan by Socialist leader Pedro Sanchez failed on March 2 as rivals on the left and right voted against it in parliament. Rajoy has refused to attempt to form a coalition, claiming he lacks the necessary support.
The El Mundo poll showed support rising support for both Ciudadanos, up 12 seats from December, and the PP, with five more seats than in the elections, at the expense of other newcomer, anti-austerity party Podemos (We Can).
The El Pais poll, taken among 1,200 people at the end of March, also showed that Podemos had lost support since the December elections.
(Reporting by Paul Day; Editing by Tom Heneghan)