Malians are voting in a second round presidential election to determine if incumbent Ibrahim Boubacar Keita will remain in office.
He is facing off against opposition leader Soumaila Cisse.
Many worry that the vote could be marred by violence. In the July 29 first-round presidential vote, extremists killed three election workers and destroyed some voting materials.
Mali has grown more insecure since Mr Keita beat Mr Cisse in a second-round election in 2013.
Extremists are staging more bold attacks that have spread to central Mali, where both Islamic State and Al Qaeda-linked militants are present.
Deadly communal clashes between ethnic groups and accusations of heavy-handed counter-terror operations have caused even deeper tensions and mistrust of the state.
A second term for Mr Keita, 73, seems likely. He received 41.7% of the vote in the first round from a field of 24 candidates and has gained endorsements from some other candidates.
Mr Cisse, 68, who placed second in the first round with nearly 18% of the vote, has blamed Mr Keita for insecurity, violence and corruption. His opposition party also alleges there was voting fraud in July.
Mr Cisse has not received major endorsements from failed candidates, but does have the backing of a popular spiritual leader Mohamed Ould Bouye Haidara.