By James Ingham
BBC News, Caracas
President Chavez says changes are needed for "21st Century socialism"
Venezuelans are voting in a referendum on 2 December that will determine the future of President Hugo Chavez's ambitious and controversial political revolution.
A series of amendments has been proposed, which Mr Chavez says will speed up a process of social and economic transformation.
At the heart of the changes, he says, are proposals to give ordinary people more say in the way the country is run.
"We will only reach socialism by unleashing the power of the people," Mr Chavez has said.
But opponents say the changes will give too much power to the Venezuelan president and turn the country into a socialist state.
Led by student groups, they have run a vocal campaign for a "No" vote on Sunday.
At a march organised by the government earlier this month, hundreds of thousands of people showed their support for the "Yes" campaign.
Buses arrived in the capital from every corner of the country.
Getting off were supporters, or Chavistas as they call themselves, who said the president had improved their lives.
Chavez supporters have held big rallies in support of the changes
"Reform is the best thing not just for us but for our children" one told me.
"Chavez has taken us out of the horrible situation we were in".
Another, looking tired after an overnight trip, said:
"Every one of the changes benefits society, particularly the working class. People are being given housing, social benefits, a job, the chance to study."
The Chavistas have been promised more power and more control of their local communities, if the reforms are passed.
The structure of government will be altered, allowing the president to declare parts of Venezuela federal areas and appoint their leaders directly.
The state will expand its network of co-operatives and set up more community councils.
There will also be a new class of "social" property, which is defined as being for the public good.
The idea is to allow people to organise themselves into groups to run their own affairs, but critics say the new system could undermine the existing political system.
One popular change will see the working day reduced to six hours, giving people more free time that can be used - among other things - for learning more about being a socialist in the new Venezuela.
Indefinite re-election of president, term increased from 6 to 7 years
Central Bank autonomy ended
Structure of country's administrative districts reorganised
Maximum working day cut from 8 hours to 6
Voting age lowered from 18 to 16
Social security benefits extended to workers in informal sector
Probably the most controversial amendment is on presidential re-election.
As the law stands now, Mr Chavez will have to step down in 2012 after two terms as president.
He is not ready to go so he has proposed a change that would allow him to stand for the office an unlimited number of times.
"I'm conscious of my responsibilities," he said. "I don't want to leave my work half finished".
All this worries his opponents.
Society here is divided, with many feeling Mr Chavez is becoming too powerful and making life difficult for those who do not agree with his vision.
The retired head of Venezuela's military and ex-minister of defence has voiced these concerns clearly.
General Raul Baduel had been with Mr Chavez right from the start.
He stuck by the president when he was ousted in a short-lived coup in 2002 and was instrumental in getting him back into power.
General Baduel says the changes are a coup against the constitution
But for General Baduel, this latest stage of the revolution is one step too far.
"This is a constitutional coup," he said. "This is all about power. The power of the president".
The government's emphasis on socialism has also upset many people.
The word is repeated many times in the text of the constitutional reforms.
Venezuelans will also be obliged to work to create "the best conditions for the construction of a socialist economy".
"Everything is being restricted," says Alfredo Romero, a human rights lawyer working in Caracas.
"You're losing basic freedoms and if you're not socialist you won't be able to be part of the Venezuelan system if the constitution is approved."
Perhaps most vocal in their opposition are students.
They have come into direct confrontation with the government in numerous demonstrations against the reforms.
Most protest peacefully, but a few have clashed with police and soldiers.
People opposing the changes held a final rally on Thursday
The government has labelled them as fascists intent on destabilising the country.
But it is clear from the tens of thousands who have joined rallies that this is a group that will not fade away.
"We have to fight for our future, for our rights," said Yon Goicoechea, a student leader, at a rally earlier this month.
He had just joined hundreds of others at the gates of Caracas's Catholic University as a group of government supporters passed by on their rally.
Separated by metal fences and a line of armed riot police, both groups shouted insults and chants at each other.
"We have to do what we have to do," Yon told me.
"If we don't fight for our freedoms, we won't be able to take part in a democratic Venezuela in the future."
While the vast majority of students at Venezuela's traditional public and private universities are against the reforms, those studying in newly established government-run organisations back the President.
"People are being given more opportunities to study thanks to Chavez," Farias Echeverri told me at a vigil in the capital.
To a background of revolutionary chanting, he explained how in the past it was difficult for people from poor backgrounds to get into universities.
This reform plan is widely regarded as one of Mr Chavez's boldest and most controversial moves so far.
It is also one of his riskiest.
Opposition political parties who struggled in the past with division and infighting, seem to be more united and they're pushing hard for people to vote rather then abstain as many have in the past.
Mr Chavez knows he is not guaranteed to win.
For the first time he is heading into an election without a clear lead, at least according to some polls.
But a huge political machine has rolled into action to muster support.
Red T-shirts are being distributed liberally, while giant posters with the words "Yes" decorate every official building and lamppost throughout the city.
Any normally loyal supporters who love President Chavez but have reservations about the reforms are being told:
"This vote is for me. Those who vote 'No' are against me".