(Bloomberg) -- Guinean voters are headed to the polls to pick a president Sunday after widespread protests over the incumbent’s bid to extend his 10-year rule.

President Alpha Conde, 82, and former prime minister Cellou Dalein Diallo, 68, are the frontrunners in the 12-man race to lead the world’s top bauxite producer. Conde, who’s beaten Diallo twice before, is seeking a third term in office after a referendum in March paved the way for him to run even though the Guinean constitution imposes a two-term limit.

Conde’s edge stems from his incumbency, a well-funded campaign and backing from Russia, whose companies have invested heavily in mines to extract the nation’s bountiful iron-ore and bauxite reserves. Conde and his ruling Guinean People’s Rally have pledged to attract $25 billion to the mining sector over the next 10 years.

Diallo, of the Union of Democratic Forces of Guinea, was the runner-up in the 2010 and 2015 elections. He’s pledged to get the mining code amended so the people reap more benefit from the country’s mineral wealth. He has also said the country would diversify into iron, uranium and copper production, if he became president.

The lead-up to the vote has been fraught, with protests against Conde’s third-term bid and the two main parties tapping into long-standing ethnic divisions.

United Nations Secretary-General Antonio Guterres urged “the country’s political leaders and their supporters to refrain from acts of incitement, inflammatory language, ethnic profiling and violence” in an emailed statement late Saturday.

Some 5.4 million voters are registered to vote, with polling stations scheduled to close at 6 p.m. local time.

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