|Chavez has faced vocal and persistent opposition to his government [EPA]
What are Venezuelans voting on?
Venezuelans are set to vote on Sunday in a referendum that would end the limit on politicians' terms in office, allowing Hugo Chavez, Venezuela's president, and others to stay in power as long as they keep winning elections.
Chavez lost a referendum on constitutional reforms that included the same proposal in 2007.
What is the government's case?
The Venezuelan leader says he needs at least another 10 years in power to push through his reforms, which includes spending on health and education, land redistribution to the poor and nationalisation of key industries.
Chavez also says he needs more time to build what he calls "21st century socialism" by pumping billions of dollars into social projects for the poor.
What do the opposition say?
The opposition says that giving any politician the power to remain in office indefinitely raises concerns about the future of Venezuelan democracy.
Some have accused Chavez of becoming increasingly autocratic and of seeking to govern in the same way as his idol, Fidel Castro of Cuba.
They also complain that Chavez has unfairly used state power to make his case in the media and in public places.
Who is likely to win this time?
Chavez has a tight lead in some opinion polls but many say the result is too close to call.
The Venezuelan leader, who is confident of victory, has maintained his popularity among the poor but the opposition has also made gains, strengthening its position in regional elections last November.
How would a Chavez victory affect Venezuela?
A victory would strengthen Chavez's mandate and give him greater confidence to expand his socialist-style policies, including the nationalisation of key parts of the Venezuelan economy.
But winning the vote could also allow him to take unpopular economic measures such as spending cuts or new taxes.
The nation relies on its huge oil resources for much of its income and the global price of oil has plummeted in recent months.
What could happen if he loses?
A loss would strengthen opponents with a second clear victory over Chavez's right to run for re-election again.
Opposition leaders could then also request another referendum against him in 2010.
A weakened Chavez could respond by slowing the pace of his reforms, as he did in early 2008 after he lost the 2007 referendum.