Carles Puigdemont (right) and ERC leader Oriol Junqueras (left) attend a protest in Barcelona in October 2017 | Quique Garcia/EPA Catalan separatists to contest election separately As Carles Puigdemont’s party sinks in polls, his erstwhile allies prefer to compete alone in the December regional vote.

MADRID — Catalan pro-independence parties are set to run on separate platforms in a regional election on December 21 after missing an official deadline for presenting coalitions this week, which could ruin ousted regional leader Carles Puigdemont's chances of a comeback.

Puigdemont has repeatedly advocated for a joint list of secessionist parties from his current refuge in Belgium, where he is trying to avoid detention after Spain issued a European Arrest Warrant on sedition charges. The former regional president has said he would be prepared to take part in another pro-independence coalition, contradicting his previous assertions that he would not run for office again.

However, after Tuesday's deadline came and went, it was clear that his arguments did not convince his erstwhile coalition partners from the Catalan Republican Left (ERC), which polls put in first place ahead of the ballot. Analysts say the ERC has more to lose than to win from a new alliance with Puigdemont’s center-right Catalan European Democratic Party (PDeCAT).

“The ERC didn’t want a joint list and it’s logical that they didn’t want one,” said Nacho Corredor, a political consultant, adding that a renewed coalition would only have benefited Puigdemont’s PDeCAT, which currently polls fourth.

Technically, there’s still a chance the independence parties could present some degree of unity. Catalan political forces have until November 17 to present their lists and they could still run under a rarely used legal construct called a “grouping of electors,” although the chances appear slim. While one national lawmaker for the PDeCAT didn’t rule it out completely, a senior official from the ERC leadership said it was “impossible.”

"A joint list was bad business" — Pablo Simón

It’s unclear if a joint separatist platform would increase the parties' chances in any case. Although the electoral system rewards the concentration of votes, alliances can repel voters as well as attract them. For example, leftist voters may be reluctant to choose a list that includes right-wingers and vice-versa.

“A joint list was bad business,” said Pablo Simón, a politics professor at Madrid's Carlos III University, pointing to the Catalan regional ballot in 2015, where the joint PDeCAT-ERC list got fewer seats in the regional parliament than the sum of both parties in the previous election.

That leaves Puigdemont with the option of leading his party to a humiliating defeat or giving up on the idea of running altogether.

A poll by Catalan newspaper La Vanguardia on Saturday placed the ERC first but didn’t guarantee the separatists an absolute majority in the regional assembly. The liberal Ciudadanos and the Catalan Socialists — both parties opposed to the latest independence bid — ranked second and third respectively ahead of Puigdemont’s PDeCAT. Other polls, however, do predict a pro-independence majority as in 2015.

Supporters of continuing the union of Catalonia and Spain see December's vote as a potential turning point.

Spanish Prime Minister Mariano Rajoy said Wednesday he hoped the ballot would mark “the beginning of a new era” of “tranquility, security and certainty for citizens.” In a statement to the Spanish Congress, he urged people in Catalonia to grasp the importance of the vote and register a “massive turnout.”

That hope is shared by other unionist supporters, who recall that traditionally low turnout in regional elections has tended to favor Catalan nationalist parties while when turnout is high in national votes, anti-independence parties like the Socialists have performed better.

The leader of Ciudadanos in Catalonia, Inés Arrimadas, told reporters this week that secessionist parties face a crisis of political narrative after their failed push for independence in the past two months. “They’ve built up a great lie” and don’t know what to tell voters now, she said.

The Catalan Socialists, for their part, announced an electoral deal with a fringe Catalan nationalist party, Units per Avançar, which champions greater autonomy for Catalonia but not independence. The Socialists' hope is to poach votes from moderate nationalists who are disenchanted with the current level of confrontation and favor softer strategies for obtaining more autonomy.

“It’s a risky maneuver, but one that it makes sense to explore,” said consultant Corredor, pointing to the fact that 100,000 people voted for the fringe party in 2015, although that was not enough to win any seats in the regional assembly.