Voters in São Tomé and Príncipe go to the polls for a presidential election on Sunday as one of Africa’s least populous countries seeks to burnish its democratic credentials.

According to the National Election Commission, about 142,000 people are registered to vote in the tiny African state’s elections, approximately 15% of whom live in the diaspora.

Since gaining independence from Portugal in 1975, the island country off Africa’s west coast has built a solid reputation for peaceful, competitive elections. But this year’s vote comes amid a tense political atmosphere and a lingering constitutional crisis.

The president, Carlos Vila Nova, is running for a second term as an independent, rather than as the candidate for the ruling Acção Democrática Independente (ADI), whom he represented when he was elected in 2021.

The tensions between Vila Nova and his former party began in January last year when he dismissed the prime minister, Patrice Trovoada. Trovoada’s replacement, the former justice minister Ilza Amado Vaz, resigned after just three days, before the current holder, Américo Ramos, took office.

On Sunday, Vila Nova will be running against four other candidates including the ADI parliamentary leader, Nito D’Abreu. Another former prime minister, Jorge Bom Jesus, attempted to withdraw his independent candidacy, but missed the deadline and remains on the ballot.

The main opposition party, the Movement for the Liberation of São Tomé and Príncipe, is now part of a broad coalition backing the incumbent president, despite being staunch ADI opponents. Meanwhile, an ADI faction led by Ramos is backing D’Abreu. If no candidate receives more than 50% of the vote, the election will go on to a second round.

The businessman Domingos Monteiro, known as “Nino”, who has been president of the São Toméan Football Federation since 2015, was disqualified after the constitutional court ruled he did not meet the eligibility requirements. Monteiro was born on the island, but his parents never became naturalised citizens after moving from Cape Verde where they were born.

“The constitutional court is violating the principle of equal rights … It is time for descendants born in São Tomé and Príncipe to say no to discrimination, to the culture of xenophobia and persecution,” said Monteiro.

For voters, priorities include tackling government corruption, high inflation, severe youth unemployment, chronic fuel shortages, and frequent blackouts. Rivals of Vila Nova are hoping this will keep him from a second term and propel them to the presidency.

Corruption in São Tomé and Príncipe “is the greatest catastrophe the country has experienced in this half-century [of independence”, D’Abreu said at the presidential debate on Tuesday.

The country is seen as a trusted western ally for security and maritime trade in the Gulf of Guinea, one of the world’s biggest maritime piracy hotspots. It also has offshore oil deposits that make a significant contribution to its economy. Observer missions from the European Union, G7+ and the Community of Portuguese Language Countries are on the ground to monitor the polls.