Bolivians head to the polls Sunday for elections that could spell the end of the long reign of the leftist Movement Toward Socialism party and see a right-wing government elected for the first time in over two decades.

The election is one of the most consequential for Bolivia in recent times - and one of the most unpredictable. Even at this late stage, a remarkable 30% or so of voters remain undecided.

Polls show the two leading right-wing candidates, multimillionaire business owner Samuel Doria Medina and former President Jorge "Tuto" Quiroga, locked in a virtual dead heat.

The elections are taking place amid the country's worst economic crisis in four decades.