Venezuela's student movement is once again breathing life into the country's opposition, 15 months after helping to inflict President Hugo Chavez's only national election defeat in 10 years.
The students are back to battle a second attempt by Chavez to scrap electoral term limits, after helping to beat his first bid in December 2007.
They paint their hands white in a symbol of peace and meet in university gardens.
They have "stamped an air of freshness on the opposition movement that has a very marked link with the past," said Leoncio Barrios, a social psychologist.
Many members of Venezuela's opposition are linked to the political class that once held power, who carried out a brief coup against Chavez in 2002 and led a nationwide oil strike that paralyzed the country later that year.
Five years later, university students were the most active in protests against the failure to renew the licence of a popular TV station that criticized Chavez, before leading the successful campaign against the president's first bid for unlimited terms.
Polls suggest a tight fight for on Sunday's referendum, although Chavez seems to have a slight lead.
In a sign of the stakes, government forces broke up two student marches recently with tear gas and arrests, and refuse to authorize many further protests.
"In the public's imagination, the university students represent hope," Barrios said. "By their own nature, the students have been a vanguard opposition movement."
Chavez's government has responded by presenting its own student supporters, and labelled opposition students as "spoilt kids" and "violent."
In a symbolic message, the president last year named a former student who supported him during the last opposition protests as a government minister.
But student government supporters are only dominant in recently created, government tied institutions.
"The government is most worried by the fact that it lacks a new generation of young people to defend them," said Juan Pablo Lopez, a student leader from Venezuela Central University.
The opposition dominates in autonomous and private universities and has mobilized some 15,000 students to campaign for a 'no' vote on the constitutional changes on Sunday, and to help oversee the poll.
"Our role is to promote the vote and defend the results. We want more than 11 million voters to turn out (out of some 17 million). We want to reduce abstentions," said student Rafael Bello, of the Andres Bello Catholic University.
The student movement is more pragmatic than those of 1968 that inspired it, Barrios said.
"There's a coordinated group of organizers. It's not a completely spontaneous movement."
The students have become one of the main concerns for the government and Chavez, who is prepared to confront them, said analyst Luis Vicente Leon from the Datanalisis polling company.
"He'll try to lead them to a dead end, in which they'll lose if they turn to violence, and if they don't fall, they'll still be cornered," Leon said.