announced Wednesday that the centrist Ciudadanos party would back their candidate for prime minister, ending weeks of political deadlock since inconclusive elections.

"In 45 minutes we will present the document," said Antonio Hernando, the lawmaker who is leading the Socialist team negotiating a coalition deal with other parties. "Obviously the deal implies a vote in favour of the investiture" of Socialist leader Pedro Sanchez.

Spain has been in political limbo since an inconclusive election in December left a hung parliament split among four main parties, none of which has enough seats to govern alone.