Spain's new parliament met for its opening session Tuesday, with the far-right Vox as the third-largest party following a divisive election that failed to resolve years of political deadlock.
Just over three weeks after the vote, lawmakers were on Tuesday taking the oath of office, although there was little indication of when a government would be formed.
The legislature has been gridlocked since an inconclusive April election which the Socialists won but without a majority -- in an outcome repeated on November 10, leaving Pedro Sanchez a winner but weakened.
And this time round, Vox -- which only a year ago was just a marginal player -- more than doubled its showing, snaring 52 mandates and becoming the third-largest faction within the 350-seat parliament.
Days after the election, Sanchez and the radical leftwing Podemos agreed in principle to form a coalition government.
But such a government would only have 155 seats, leaving it dependent on support from other factions for the 176 mandates to pass an investiture vote.
Last month, Sanchez's negotiating team began talks with the Republican Left of Catalonia (ERC), a Catalan separatist party which won 13 seats in November's election.
But so far it has refused to offer its backing, demanding in exchange talks on the Catalan crisis which would likely include its call for a referendum on self-determination -- an idea Madrid has rejected out of hand.
- 'Unstable govt' in the making -
ERC is headed by Oriol Junqueras, one of nine Catalan leaders handed heavy jail terms in October over a failed 2017 independence bid in a move which sparked a wave of mass protests, some of which turned violent.
ERC and the Socialists are due to meet again on Tuesday, with Eurasia analyst Federico Santi saying a deal between them "remains likely" although the talks "will probably drag on for several weeks".
Even so, the outcome would be a government which would be "inherently unstable and ... unlikely to last for a full term", he said.
But opposition to the proposed coalition, notably from business leaders over a government including Podemos with support from the separatists, has sparked growing calls for Sanchez to talk with the rightwing opposition People's Party (PP).
During Tuesday's session, MPs reelected Socialist Meritxell Batet as parliamentary speaker, while Pilar Llop, a judge specialising in gender violence who has ties to the Socialists, was chosen as president of the Senate.
Spain's Prime Minister Pedro Sanchez is still trying to work up support for his proposed coalition government with the radical leftwing Podemos
Composition of the Spanish parliament