Clashes in Nigeria between farmers and seminomadic herders have killed more than 3,600 people since 2016, most of them this year, Amnesty International said on Monday, in a report documenting an upsurge in violence that could sway the results of February 2019 elections.

Muhammadu Buhari is seeking a second term in those elections, but his campaign has taken a hit from accusations he has soft-pedaled justice for one of the sides responsible for the clashes — the herders — many of whom come from the same Fulani ethnic group as the leader.

The presidency has repeatedly denied those allegations.