Chileans are preparing to return Michelle Bachelet to the presidency, hoping she can fulfill promises to reform a dictatorship-era system they blame for keeping the working classes poor and indebted to the privileged few.

Chile is the world's top copper producer and its fast-growing economy, low unemployment and stable democracy are the envy of Latin America. But millions of its citizens have taken to the streets in recent years, venting their frustration over the huge wealth gap between the rich and poor and a chronically underfunded education system.

Bachelet, 62, left office with sky-high approval ratings after her 2006-2010 presidency despite failing then to bring about major changes in society.

Her closest rival in Sunday's vote is her childhood friend, conservative Evelyn Matthei.