MADRID (Reuters) - Spain's anti-austerity Podemos party said on Friday it would only start negotiations to form a government with the Socialists and end months of political deadlock if leader Pedro Sanchez abandoned talks with the centrist Ciudadanos.
The stance, taken by Podemos leader Pablo Iglesias, threw up a road block to Sanchez' attempts to win support for a viable coalition, only days after he was formally nominated to try to replace the center-right People's Party (PP).
It also supposes further delays in what has already been a drawn-out process that risks eventually weighing on the country's economic recovery.
Spain was plunged into political uncertainty after an inconclusive election in December in which no party won a majority of seats. Newer parties, particularly Podemos and Ciudadanos, grabbed votes from mainstream rivals.
Iglesias said if Sanchez wanted a pact with Podemos he would have to stop talks with Ciudadanos, who came fourth in the December general election and whose leader Albert Rivera, who he sees as cut from the same cloth as the old ruling party.
"An agreement with Ciudadanos would be an indirect agreement with the PP," he told a news conference. "We are not going to help support a right-wing government."
"Our negotiating team will be ready as soon as the Socialists opt for a government of progress," he added.
Sanchez, who has signaled he favored a coalition of leftist parties, called at a separate news conference on Friday for Iglesias to reconsider his position if he wanted to prevent a second term for acting Prime Minister Mariano Rajoy.
The Socialist leader, who has said he needs at least a month before seeking a confidence vote in parliament, added he would maintain talks with all other leaders.
The failure to reach a coalition so far raises the prospect of fresh elections later this year. A survey showed on Thursday Podemos would replace the Socialists as the second-placed party if another ballot were held.
If Sanchez loses the confidence vote, other potential candidates would have two more months to form an alternative majority before a new national election would have to be called.
Writing by Angus Berwick; Editing by Sarah White/Jeremy Gaunt