Burundians on Thursday will vote in a referendum on sweeping constitutional reforms that would shore up the power of President Pierre Nkurunziza and enable him to rule until 2034.
With opponents cowed, beaten, killed or living in exile, there seems little doubt the amendments will pass, enabling the 54-year-old - in power since 2005 - to remain in charge for another 16 years.
The campaign period, like the preceding three years of unrest triggered by Nkurunziza's controversial but ultimately successful run for a third term, has been marked by intimidation and abuse, say human rights groups.
Opposition parties were allowed to rally for the first time since the start of the political crisis in 2015, drawing massive crowds during their "no" campaigns.
But critics say this was merely to provide a veneer of inclusivity.
"People seen as opposed to the referendum have been killed, kidnapped, beaten up, illegally arrested and held by state agents," the International Federation for Human Rights (FIDH) said on Tuesday.
Some 4.8 million people, or a little under half the population, have signed up to vote, according to the Independent National Electoral Commission (CENI), which is running the referendum.
The changes will be adopted if more than 50% of cast ballots are in favour.
The vote is taking place in tightly-controlled conditions, and a presidential decree ruled earlier this month that anyone advising voters to boycott the vote risks up to three years in jail.
The tiny central African nation, with an equally small economy, has struggled to recover from a brutal and destructive civil war from 1993-2006 that left more than 300 000 people dead.
A peace deal, signed in the Tanzanian city of Arusha in 2000, paved the way to ending the fighting and included a provision that no leader could serve more than two five-year terms.
Nkurunziza circumvented that clause by running for a third term in 2015 that critics said was unconstitutional. A crackdown on opponents of his bid prompted a crisis that has seen 1 200 people killed and 400 000 flee their homes.
The violence and abuses are being investigated by the International Criminal Court (ICC) while a sustained campaign against the press has forced most independent journalists to leave the country.
Nkurunziza - a fervent Christian who believes he has a God-given right to rule and was recently declared "visionary" by his CNDD-FDD party - now wants to rewrite the constitution and extend term lengths to seven years.
This would allow him to start again from scratch after the 2020 elections.
Other reforms weaken constitutional constraints over the feared national intelligence agency and allow the revision of ethnic quotas seen as crucial to peace after the war.
The new constitution also gets rid of one of two vice-presidents and shifts powers from the government to the president.
Burundi's exiled opposition, gathered in an alliance called CNARED, has called for a boycott of the referendum, which it describes as the "death knell" to the 2000 agreement that helped end the bloody civil war.
The government has accused dissidents, and neighbouring countries, of planning to undermine the referendum and has deployed military units to areas bordering Rwanda to the north and Congo to the west.
Earlier this month Burundi's press regulator suspended broadcasts by the BBC and Voice of America (VOA) and warned other radio stations, including Radio France International (RFI), against spreading "tendentious and misleading" information.
Amending constitutions to stay in power while holding the regular elections that foreign donors demand is a popular tactic among African leaders.
Uganda's Yoweri Museveni changed the law in 2005 before running successfully for a third term. The 73-year-old has since removed age limits and is expected to run for a sixth term in 2021.
Cameroon's Paul Biya followed Museveni's lead in 2008 and remains in power today, as does Djibouti's Ismael Omar Guelleh who removed term limits in 2010.
In Rwanda, Paul Kagame in 2015 changed the constitution and is now set to rule until 2034 while Congo-Brazzaville's Denis Sassou Nguesso also pushed through the removal of term limits the same year.
Zambia's Edgar Lungu is trying the third term gambit, while in the Democratic Republic of Congo, Joseph Kabila has simply refused to hold elections since the end of his constitutional terms 18 months ago.
Elsewhere in Africa, leaders have had less success avoiding term limits, with moves blocked or votes lost in Benin, Burkina Faso, Nigeria and Senegal in the last dozen years.