Can Gabon's opposition unseat President Bongo?
The opposition in Gabon is presenting a slightly more united front than usual in this Saturday's presidential election, raising expectations that the vote could be closer than in previous years.
President Ali Bongo Ondimba is standing for a second seven-year term, having won the hotly disputed 2009 election after the death of his predecessor and father, Omar Bongo.
It is the candidate with the most votes that wins - a system which favours President Bongo, whose main rival is veteran diplomat Jean Ping.
Last time he faced 22 candidates, this time there are nine challengers in what has been a fiercely fought campaign, which has questioned Mr Bongo's nationality.
So is the president Gabonese?
This question has been on the lips of most opposition candidates, and has dominated campaigning.
The opposition say he was born in Nigeria and adopted by his father, which the president denies.
The constitution says presidential candidates must be born in Gabon - and the Constitutional Court ruled on 25 July that Mr Bongo was indeed Gabonese.
But the row has overshadowed other issues, chief among them being the enduring poverty of most citizens despite the country's relative wealth.
Gabon has one of the highest per-capita incomes in Africa, but few of its 1.6 million people feel the benefit.
The oil-dependent economy is also under pressure because of depressed crude oil prices worldwide, and public servants have gone on strike in recent months over unpaid salaries.
The governing Gabonese Democratic Party's domination of the state system is an issue for the opposition.
Mr Ping, who has won the endorsement of the main opposition Front for Political Change coalition, says he will undertake wide-ranging political reforms if he wins.
President Bongo himself has pledged to re-introduce the limit on the number of presidential terms that was abolished in 2003.
But fundamental changes are unlikely, as both frontrunners and most minor candidates come from the elite that has governed the country since independence.
President Bongo refused to do go head-to-head with Mr Ping in a TV debate, but all the candidates have been questioned by a panel of journalists on TV this week.
Who are the main candidates?
The electoral commission approved 14 presidential candidates, but four have dropped out to back Mr Ping, making him and President Bongo the main contenders.
The 57-year-old president is a French-educated, Muslim convert serving as foreign and defence minister under his father, who died in office after 41 years in power.
His time at the helm has been overshadowed by a long-running French investigation into allegations of embezzlement involving the Bongo family's assets. The family strongly deny the accusations, but last year the president promised to give away all the money he inherits from his father, to set up a foundation for the country's youth.
His re-election bid has not been plain sailing, causing a split in the Gabonese Democratic Party, with dissenters leaving to form the opposition Heritage and Modernity Rally party.
Mr Ping, whose father was Chinese, also served as foreign minister for Omar Bongo - and has close links with family. He went out with his eldest daughter and the couple have two children together.
One of his most high-profile positions was chairing the African Union Commission for four years until 2012. Two years later he left the governing party to join the Front for Political Change.
The 73-year-old has won the backing of two opposition heavyweights who were also both former allies of the Bongo family: Casimir Oye Mba, a former prime minister, and ex-parliament speaker Guy Nzouba Ndama.
Another two candidates have also withdrawn in his favour.
A handful of candidates, like 49-year-old Bruno Ben Moubamba, try to embody the new generation of politicians, but their weakness lies in the lack of financial resources and popularity.
Has the campaign been peaceful?
The controversy over President Bongo's nationality has sparked sporadic violence, especially in the capital, Libreville.
Security forces clashed with protesters in early July and made some arrests, and broke up another opposition protest later in the month. Police numbers and night-time checks have increased in the city.
President Bongo has accused the opposition of "inciting the people to disagree and indulge in violence" and has ordered the security agencies to "take all necessary measures" to make sure the vote goes smoothly.
Mr Ping says the president has recruited "mercenaries" ahead of the vote, which Mr Bongo can only win "through fraud".
Who is likely to win?
The president's control of the machinery of state gives him the advantage, and he only has to receive one vote more than Mr Ping to be declared the winner.
The opposition has already raised concerns, accusing the authorities of having "ready-made results".
Mr Ping says his "anti-fraud brigades" will monitor the vote closely.