As talks with anti-austerity leftists Podemos have failed to get off the ground, Spain's center-left PSOE is increasingly looking at other options to end more than a month of political deadlock.

Leader Pedro Sanchez is not taking the decision lightly. On Saturday, he said that party members would be polled about what to do.

However, one decision - that of whether a Grand Coalition between should be formed - has been made.

Such an alliance, involving PSOE and the conservative Partido Popular (PP), or Popular Party, would be preferred by acting Prime Minister Mariano Rajoy. While the PP is the single largest party in parliament, it has too few political allies on the right to consider anything else.

However, Sanchez has dismissed the idea, saying he prefers to pursue a "progressive and reformist" agenda.

PSOE lawmaker Pedro Saura agrees that the idea of a coalition with the PP, which has become mired in a series of corruption scandals, would be disastrous.

"We think that would be a fraud against the people," Saura told DW. "They have done a lot of harm when it comes to inequality and it's a party with a level of corruption that is systemic."

As talks with Spanish King Felippe VI and party leaders have continued, it has looked increasingly likely that Sanchez might be invited to try to form a government.

Apparently suitable allies

The obvious thing would be for PSOE to team up with the new leftist Podemos. Its anti-inequality, anti-corruption agenda would appear palatable enough.

However, Podemos - led by the youthful pony-tailed Pablo Iglesias - has insisted on a referendum on Catalan independence, and that's something PSOE can't swallow. Influential Socialist regional leaders - such as Andalusia's Susana Diaz - have categorically rejected an alliance with Podemos while the referendum question is on the table. And so, talks have stalled.

While PSOE says it is being blackmailed, Podemos claims its referendum policy is not a red line, but a "firm conviction" that is open for debate.

Podemos told DW that its intention was to "halt the politics of territorial polarization of the PP," explaining that it was serious about forming a government with PSOE.

"Podemos has proposed to PSOE to form a government of change in favor of the social majority," the party said in a statement. "Our proposal lays the foundation for what we view means a change - reducing inequality, helping citizens, carrying out tax reforms and implementing a plan of economic modernization."

Vying for dominance of the left?

Even if the two parties could team up, they would still need the support of Basque and Catalan independence parties. They would likely block any vote until they were offered a binding referendum on independence.

"I think the message that is coming from Podemos is that there are no red lines, including the Catalan referendum," Vincenzo Scarpetta, southern Europe analyst at the Open Europe think tank, told DW. "My view is that what Podemos are really trying to do is to make it difficult for the socialist party to accept this offer, because the ultimate plan for Podemos is to become the main left wing party in Spain, so they want to overtake the Socialist party, they don't really want to prop it up in a coalition."

An eagerness to talk

Perhaps preferable for PSOE would be an alliance including new era conservatives Ciudadanos - which came fourth in the December 20 elections - and Podemos. Both of the parties that broke Spain's decades-long two-party dominance have campaigned strongly against corruption.

"PSOE wants to talk about a program of government that is progressive and reformist," PSOE's Saura told DW. "We want to speak to the parties that are progressive and reformist, and not those seeking independence." Ciudadanos is a party that has gone with a program that takes the line of reforming institutions in the fight against corruption. "We would like to speak to them, and we would like to reach an agreement."

However Ciudadanos has already ruled out any coalition that involves Podemos. As far as Scarpetta is concerned, it could never work anyway.

"On economic policy, they are very far from each other," said the analyst. "Apart from the anti-corruption measures, it's difficult to see these two parties agreeing on anything else."

When the countdown begins

Despite the ongoing political uncertainty, the real crunch time - when the concerned parties might feel more urgency to make compromises - could arrive when one of the two larger party leaders - Rajoy or Sanchez, submits themselves to a vote of confidence at an investiture session.

Failure to win would trigger a two month countdown - at the end of which, if there were no agreement, fresh elections would have to be called.

"The main thing for the socialist party is to avoid rerun elections because they stand to lose the most of all the political parties in rerun election," Scarpetta said.

"If I had to put my money on a scenario, what I would see is that the Socialist party tries to form a government with Podemos, they realise it's not possible without the support of the Catalan separatist parties and therefore they agree, reluctantly, to let the Partido Popular form a minority government."

"I think the Socialist party is in the toughest position at the moment of any of the parties. They have two offers - if they fail to take either then there will be new elections and the socialist party will be singled out by other parties as the one to blame for uncertainty and forcing new elections and it could lose further in these elections."