Ahead of Sunday's presidential election in Sao Tome and Principe, two candidates are vying to succeed Evaristo Carvalho, president since 2016, who has decided not to run again.
The president has largely ceremonial powers, he may arbitrate disputes but does not govern.
The first round was held without major incident, July 18. The outcome of the vote has been disputed.
Carlos Vila Nova of the center-right opposition Independent Democratic Action (ADI) party led the first round of voting on July 18 with 43.3 percent of the vote.
His opponent for the runoff is Guilherme Posser da Costa of the center-left Movement for the Liberation of Sao Tome and Principe (MLSTP) party, who scored 20.7 percent.
The third-placed candidate, Delfim Neves, had alleged fraud during the ballot and demanded a recount.
Carlos Vila Nova and his supporters had also questioned the results suggesting that Nova's actual support was higher than the official National Electoral Commission (NEC) result of 39.4 percent.
The country is a former Portuguese colony of 210,000 people that is widely considered a beacon of parliamentary democracy in West Africa.