A radical left party has made a startling journey from colorful oddity to potential kingmaker in Catalonia's independence drive.

The Popular Unity Candidacy joins a line of far-left movements seizing the political momentum in Europe, from Greece's ruling Syriza party and Spain's own far-left Podemos movement to the shock emergence last week of hardcore socialist Jeremy Corbyn as leader of Britain's Labour Party.

As in the other cases, painful austerity policies have given wings to the CUP — and it finds itself possibly holding the key to the aspirations of Catalan separatists determined to sever centuries-old ties with Spain.

Catalans vote Sunday in regional parliamentary elections that the breakaway camp hopes will give them a mandate to put their region on a path toward independence — a goal the Madrid central government says would be illegal.

Polls show the race is tight and that the large "Together for Yes" block formed by pro-independence parties from the rest of political spectrum will need support from the smaller CUP to secure a 68-seat majority in Catalonia's 135-seat parliament. And without the majority, secessionists concede, the effort to break away from Spain will be set back for years. That gives CUP potentially strong leverage to dictate the terms of its support, and impose some of its hard-left agenda on business-friendly Catalonia.

CUP is present only in northeastern Catalonia and is led by the outspoken David Fernandez, who sports T-shirts with radical slogans (from his wardrobe of more than 200), while debating in the ornate chambers of Catalonia's Parliament.

Under the 41-year-old Fernandez, the party has succeeded regionally in tapping into the same anger at Europe's austerity measures that has vitalized far-left European parties like Syriza in Greece that eat into traditional support for social democrats. Polls show CUP set to win as many as 10 parliamentary seats, up from the three it currently holds.

Catalans, he said in an interview with The Associated Press, need to claim their sovereignty as a nation from a Spanish state he insists has little respect for Catalonia and is an enthusiastic participant in a global capitalist economy he labels as "a war machine that robs, kills and lies."

Movements that inspire Fernandez include Syriza, Ireland's Sinn Fein, Spain's Basque Country separatists and the Zapata Army of National Liberation active in Mexico's Chiapas region in the 1990s. But he said CUP owes most of its identity to Catalonia's own history of workers and leftist movements, including 1930s radicals from pre-dictatorship Catalonia — when anarchists, communists and militant workers unions were among those who fought a losing 1936-39 war against Francisco Franco's fascist forces.

After earning a reputation as a gifted debater in parliament, Fernandez and CUP's radical rhetoric have struck a note with pro-independence Catalans who are angry about the languishing economy and firm in their belief that Catalonia does not get back what it pays in taxes to Madrid.

Fernandez has consistently polled as Catalonia's "highest rated" politician in regional government surveys since he joined the chamber in 2012. But the central government in Madrid cites his radical views as one of many reasons why voters should choose anti-independence regional lawmakers.

He brushed off claims that Catalonia would have a rough ride trying to turn itself into a nation and described Spain as a failed state.

"We are already having a rough time right now," he said. "We have to recover the public sector, we have to scare the free market out of our pensions, education, health care, and culture, and let the cooperative social sector come in and combat the casino economy of capitalism and financial speculation."

Analysts say the economic hardship is the main reason why CUP and other radical parties around Europe have gained power. In Spain, crushing austerity measures, a 22 percent unemployment rate and prominent corruption cases involving politicians from Catalonia and across Spain "has been the perfect storm, and the crisis has really helped" CUP, said Antonio Barroso, a London-based analyst at the Teneo Intelligence political risk consultancy.

Corbyn's overwhelming victory in Labour's leadership election was one of the biggest shake-ups in British politics in decades. Meanwhile, Portugal's Communist Party has support of as much as 10 percent of the electorate — and could help deny that country's Socialist Party a shot at taking back power from the governing center-right coalition in an Oct. 4 election.

"Austerity and the economic crisis have given a window of opportunity for extreme left movements to increase their level of support," said Barroso. "They can influence the debate but the question is whether they can influence the decision-making."

CUP has even welcomed warnings that an independent Catalonia would be kicked out of the European Union, a threat which polls show make many Catalans think twice about going their own way.

For Fernandez, an exit from the EU would be an escape from a group it claims is ruled by capitalists bent on exploiting the working class.

"We think that the dilemma of our time is whether this is an age of the markets or this is an age of the people," Fernandez said. "We don't recognize any authority for the troika. Nobody chooses the IMF, nobody chooses the European Central Bank, and states and bankers in ties choose the European Commission."

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Associated Press writer Alan Clendenning contributed to this report from Madrid.