BARCELONA — In a mass demonstration of youth and enthusiasm, thousands of students marched down the Gran Via here Thursday afternoon, presenting the well-scrubbed face of a separatist movement hoping to sever the Catalonia region from Spain.
The rally, the largest in recent memory, featured throngs of university and high school students draped in Catalan flags and protected by cadres of sympathetic firefighters in yellow helmets.
The young people took selfies, smoked a little marijuana and plastered signposts with posters featuring cartoon characters.
The atmosphere was festive, raucous, contagious — with folk songs from a generation ago. When elderly supporters came out on their balconies to bang pots and pans in support, the students stopped to honor them with chants: "No revolutions without the grandmothers!"
But the situation is growing serious.
The secessionist leaders here are pressing forward with their promise to stage a controversial referendum Sunday that asks a seemingly simple question: Do you want Catalonia to become an independent state, in the form of a republic? Yes or no.
The central government in Madrid, led by Prime Minister Mariano Rajoy of the conservative Popular Party, says the plebiscite violates Spain's 1978 constitution that declares the country indivisible — and therefore is illegal.
The Rajoy government, backed by constitutional court rulings, has vowed to stop the vote, and it has deployed thousands of national police and paramilitary Guardia Civil officers to the region.
"We have no idea really what will happen Sunday. But it's hard to see a peaceful ending, no?" said Pablo Sanchez Crespo, 21, a psychology major hunkered down in the courtyard of Barcelona University, which has been occupied by striking students sleeping on mattresses and swinging in hammocks.
"If they want to stop the vote, they are going to have to put many, many cops at the polling stations, and if the people still want to vote? I don't know," he said. "I think there will be trouble."
A few minutes earlier, Jordi Graupera, a professor and pro-independence activist, was conducting a 2017 version of a U.S.-style 1960s teach-in in the courtyard, explaining to students the concept of civil disobedience and telling them of the winning tactics of Martin Luther King Jr.
"You don't have to attack anyone," the professor said. "But you have the right to resist."
He encouraged the students, if they were willing, to occupy and defend polling places — school gymnasiums, community centers, city halls — and to bring plenty of food and water.
The professor said they would not go to jail for forcing open the polling spots but might be fined.
The showdown between the prosperous but restive region of Catalonia and the distant central government in Madrid could become Spain's most profound political crisis since the end of the dictatorship of Gen. Francisco Franco four decades ago.
A lot depends on the next few days — and which side yields, and who is seen as oppressed or oppressor. Many editorialists in Catalonia describe the impasse as two locomotives rushing toward each other on the same track.
On Tuesday at a news conference, President Trump said, "I think that Spain is a great country, and it should remain united."
A dozen Catalan functionaries have been arrested, charged and released. The police have raided warehouses and printing presses, and confiscated 13 million sheets of paper — including ballots.
Many of the students interviewed mentioned Franco and his 40-year oppression of Catalonia's language, culture and autonomy as a rallying cry.
Asked what he knew of
Franco, who died in 1975, a quarter-century before he was born, Marc Garcia said, "We heard all about it from our parents and grandparents."
Garcia and his friend Judit Marti, both 17, said they also had been informed and stirred by programing on the public broadcaster, TV3, which is sponsored by the Catalan government.
Some of the students said they thought the current standoff was a legacy of the Spanish civil war in the 1930s and the unfinished business left after Franco's long reign.
"Franco didn't lose this war — he just died," said Pau Subirana Garcia, 21, a computer science student. "All the people around him are still around."
Subirana was carrying a black flag with a star and cross, which he said dated to the 1714 Siege of Barcelona. "The black is about no surrender," he explained.
The student said many friends care less about whether Catalonia chooses independence than that they have the right to vote. "Our ancestors gave their lives for these freedoms," Subirana said. "It shouldn't be a crime to vote. We won't do anything bad."
Polls this summer showed that more voters in Catalonia would choose to remain in Spain than strike for independence — but moves by the central government considered to be heavy-handed may have shifted sentiments.
The students occupying the university and joining the rally spoke with passion, especially about their right to vote, but they were unsure exactly what independence would bring.
Catalonia pays an oversize share of its taxes to the central government, but the region enjoys fairly broad autonomy and controls its own police, education, health care, schools, parliament and media. The dominant language is Catalan.
There are now so many police from outside the region in Catalonia that the Spanish government chartered two commercial cruise ships and docked them in the Barcelona port to berth the overflow.
One of the ships sports large cartoon drawings on its hull of Looney Tunes characters Daffy Duck, Wile E. Coyote and Tweety, and the yellow bird has been adopted by the students as their symbol of resistance.
At Barcelona University, a pair of large photocopy machines sat in the hallway, churning out ballots for Sunday's election. The students had erected tables to pass them out. How such votes would be counted — and seen as legitimate — is unclear.
"I know lots of friends — they say yes or no about independence. But the response cannot be to send in the police against the people. That means force wins," said Elisabet Lliteres Deia, a student who said this was the biggest youth rally she had seen in Spain.
She was marching with two friends. The three represented a mix of yes, no and unsure votes. They also believed that the referendum was not binding.
Catalan politicians, however, have vowed that if more than 50 percent of ballots read "yes," the regional parliament will declare independence within 48 hours, no matter the size of the turnout or whether the vote is disrupted.
Many in Catalonia and Spain suspect that this is a bluff and that low participation would weaken the leverage of separatists.
Fully exiting from Spain almost certainly would be a long and arduous process — even if the people willed it.
Can Madrid stop the vote?
On Thursday, Catalonia's interior minister said the region's own Mossos d'Esquadra police force will act to protect public safety, but it would be impossible to stop thousands from gathering to vote. Catalonia's president, Carles Puigdemont, vowed the plebiscite would happen no matter what.
Raul Gallego Abellan contributed to this report.