(CNN)Vox, the new and fast-growing far-right party in Spain, shot to prominence after helping to form a coalition government in Andalusia after regional elections in December 2018.
Now there's a chance the party could replicate that success across the country and support an unprecedented national coalition government following Sunday's general election.
The result in Andalusia was a shock in an area where the Spanish Socialist Workers' Party (PSOE) party had governed since 1982. But Vox's extremely socially conservative, yet economically liberal, policies could yet further capitalize on a critical political juncture both in Spain, and more widely across Europe.
Vox is part of a continent-wide shift to the right and its emergence has ended the idea that Spain was somehow immune to the trend. "Spain was the only country without an influential far-right party, but that has changed," said Joan Botella, professor of political science at the Autonomous University of Barcelona.
Its growth has sparked protests and worries over increasing polarization in Spain, with some also drawing parallels between the party's ideas and those of former right-wing dictator General Francisco Franco, who ruled Spain from 1939-75.
Vox's results in Andalusia shocked Spain in December.
Vox's arrival as a political force also comes as Spain's traditional two-party system -- of PSOE and its right-wing rival the People's Party (PP) -- comes under pressure. Vox also fulfils some voters' desire for new political proposals that offer something different, according to José Ignacio Torreblanca, senior policy fellow at the European Council on Foreign Relations in Madrid.
"It's got a lot to do with the crisis of representation affecting all of the Western democracies," Torreblanca told CNN. "The elections are much more emotional, playing on feelings, aggravations and identities rather than policies."
Torreblanca pointed out similar trends in Italy, France and the UK, adding that the characteristics of each country determine whether these new, radical political projects emerge from the left or the right, or from above or below.
Catalan separatism sparks nationalist resurgence
In the Spanish case, it is the issue of Catalan independence -- following the province's unsuccessful 2017 breakaway bid -- that provided a rallying call for right-wing nationalism, according to Ignacio Molina, senior analyst at the Real Instituto Elcano thinktank in Madrid. "It combines the ideology of conservative nationalism, that we see across the Western world, with the Catalan crisis, which is what motivates them to form this new political force," he told CNN.
Molina and Torreblanca said the Catalan question acts as a lightning rod for worries over social issues such as abortion, which Vox opposes. Others fear the declining influence of the Catholic Church, the implementation of progressive gender rights legislation, a strong feminist movement and are concerned that traditions such as hunting and bullfighting are in danger.
Experts say that polarization on these issues has intensified as attitudes evolve faster in big cities than more traditional areas, and wealthy urban conservatives balk at what they see as excessive social progressivism under PSOE, which has actively promoted womens' and LGBT rights.
Vox ploughing its own furrow
Vox may draw on common touchstones for right-wing parties around the world, but its message also differs to suit a domestic Spanish context.
The party takes a hard line on irregular migration and has proposed building walls around Ceuta and Melilla -- two Spanish enclaves in Morocco -- to deter migrants. Torreblanca believes Spain's complex history of migration, and a relative lack of friction with migrant communities, mean that Vox has chosen to focus on the Catalan issue on the campaign trail. "I think they themselves realise that migration doesn't have much traction," he said. "They know that the Catalan question works better for them."
Torreblanca added that Vox is "a socially conservative party but it's very liberal economically," rejecting the statist economics of France's National Rally, for example. "I'd say it's a 'neocon' party in the American sense," he added.
Vox is also happy to remain in the European Union, while National Rally and the League in Italy have proposed leaving the bloc.
Vox's stated commitment to democracy also marks it out from the Fidesz party of Hungarian Prime Minister Viktor Orban and influential Polish politician Jaroslaw Kaczynski, chairman of the right-wing Law and Justice party, according to Peter Ceretti, an analyst at the Economist Intelligence Unit.
"They're not what you would call far-right in the sense of being close to say fascist ideology like the radical popular right parties further east," Ceretti said. "I would characterize Vox as a red meat, culturally conservative, Spanish nationalist party."
Vox is also known for adopting the Trump-esque slogan "Make Spain great again" as a rallying cry for supporters.
Vox has mobilized nationalist feeling in Spain.
Connection to General Franco?
For Torreblanca, people nostalgic for the days of Franco are likely to vote Vox, but the party is not authoritarian and has been careful to disavow any connections with fascism.
And Molina doesn't believe Vox represents the re-emergence of the ideology of General Franco. "It's not a Francoist party, it's a democratic party, very conservative but democratic," he said.
However Botella believes that there is a "direct connection" between Vox and Franco's ideology, with "a mix of traditional catholic conservatism, modern extreme-right and alt-right ideas."
Vox has not yet responded to CNN's request for comment.
Protests show Spanish polarization
As Vox encourages conservative Spain to rally around the flag and traditional right-wing values, others have reacted in horror to the party's views.
In January, thousands of women took to the streets in cities across Spain to protest against the rise of Vox and its stance against abortion and gender rights.
"Our rights are non-negotiable," read the campaign slogan for the protests. "Not one step back in equality."
The University Platform for Feminism and Gender Studies (EUFEM) also released a statement in January criticizing Vox over the party's attitude to gender-based violence.
EUFEM is an umbrella organization for feminism and gender studies researchers from more than 30 Spanish universities and civil society organizations.
And the far-right success in Andalusia last year "should worry us all" tweeted former Belgian Prime Minister Guy Verhofstadt, leader of the liberal ALDE group in the European Parliament, in December. "We face a battle for Europe's soul at the European elections in May," he added.
Who votes for Vox?
Experts know relatively little about Vox voters, but they appear to have been drawn in equal parts from the PP, the center-right Ciudadanos and people who previously did not vote, according to Botella.
Botella explains that the Vox's success in Andalusia could be explained by a confluence of factors that made the region fertile ground for its radical proposals: a desire for change after 35 years of PSOE rule, high regional unemployment rates and a society that is particularly attached to Spanish traditions.
Vox's hard line on irregular migration, at a time when Andalusia was struggling to cope with a surge in migrant arrivals across the Mediterranean, is another possible factor in its success.
Sunday's election will reveal whether this message resonates around the country. Botella believes that the national electorate could be put off by the messages from the campaign trail. "It appears that Spanish politics is more extreme than Spanish society," he said.
If the electorate does want moderation, the party leadership, which Torreblanca says is dominated by members of an upper class elite, faces a major challenge in attracting voters from beyond its small base. "What we are going to see in these elections is whether Vox is able to jump beyond this small nucleus of right-wing Catholic nationalist-traditionalist voters and connect with people who don't necessarily feel ultra-Catholic or nationalist," he said.
However Vox has managed to dominate the conversation on social media and on the campaign trail, said Torreblanca, who compares the packed political meetings to evangelical churches. "What they want to do is become the 'party of pride' for everyone who feels proud to be Spanish," he said.
