Zambians will decide Thursday whether to re-elect President Edgar Lungu after the country's worst economic performance in decades and a crackdown on dissent that has raised fears of unrest in the southern African country.
His main rival, in what polls suggest is a close election race, is 59-year-old Hakainde Hichilema, making his sixth run for the presidency.
Hichilema has already narrowly lost to Lungu twice: in a 2015 by-election after the death of ex-president Michael Sata and then in general polls the following year.
Lungu deployed the army following clashes between the rival supporters in the run-up to presidential and parliamentary polls, a move critics denounced as a tactic to intimidate opposition voters.
Analysts say the result of the closely fought election will set the tone for investment in the copper-rich southern African nation, where more than half of its 17 million people live in poverty.
Surveys suggest economic hardship has eroded support for Lungu, accused of borrowing unsustainably to finance flashy infrastructure projects, as living costs soared.
In the capital Lusaka, Lungu's green Patriotic Front (PF) party manifestos have dominated billboards lining newly built freeways and overpass bridges. They trumpet "achievements" in construction, agriculture and youth employment.
Opposition voters, whose party colour is red, are keeping a low profile in Lusaka, traditionally a PF stronghold.
Some of them even wear green, the ruling party's colour, to avoid trouble -- known as the "watermelon tactic".
"We do not feel that safe...there is so much intimidation," said UPND supporter William Njombo, a 42-year-old pastor volunteering at the party's headquarters.
- Human rights concerns -
Because of the Covid pandemic, only door-to-door campaigning has been allowed this year rather than mass gatherings, although politicians have rallied under the guise of mask-distribution events.
Government critics say the pandemic has been used to thwart the opposition.
Hichilema's team say they have been barred from entering several parts of the country, including the strategic central Copperbelt Province, their supporters dispersed with tear gas.
There are also concerns about a newly compiled electoral register, which some observers allege is skewed towards PF strongholds, and a controversial cybersecurity law that could be used to block the internet.
"The incumbent regime will stop at nothing to manipulate the vote," UPND spokesman Anthony Bwalya told AFP.
PF officials did not respond to several requests for comment.
Amnesty International warned in June that repression under Lungu had pushed Zambia to the brink of a "human rights crisis".
They noted the closure of independent media outlets, the jailing of opposition figures and the police killings of at least five people since 2016.
Hichilema himself claims he has been arrested 15 times since he swapped his business career for politics.
"There is apprehension," said Zambian political analyst O'Brien Kaaba, unsure whether Lungu would concede a defeat.
"The military on the streets creates new dynamics," he added.
The US embassy in Lusaka has urged the police and military to "apply the law equally and humanely" in the "competitive election".
While pre-election violence is not uncommon in Zambia, every transition of power has been peaceful since the former British colony adopted multi-party democracy in 1990.
- 'Tough moment' ahead -
Both Hichilema and Lungu are campaigning as "people's politicians" promising jobs and wealth to disillusioned voters.
"Vote for change and a better Zambia", says Hichilema's red-and-yellow manifesto, showing him in a suit and matching red tie signalling the "way forward" with his hand.
Over seven million people are registered to vote between 6:00 am (0400 GMT) and 6:00 pm, with the results expected by Sunday.
The results in Lusaka -- a city of more than 3.3 million inhabitants -- and the central Copperbelt province will be key to determining the winner.
"I pray that we will be able to keep peace," said Sydney Chilonga, a stylish 21-year-old in sunglasses who sells clothes to get by.
"I think it's going to be a tough moment for us."