Mexico's presidential election: Five things to know

A worker with the National Electoral Institute prepares for Sunday's vote in the state of Chihuahua.

(CNN)Mexican presidential front-runner Andres Manuel Lopez Obrador heads into Sunday's watershed election with a substantial lead in the polls and the hopes of a country disenchanted with rampant corruption and escalating violence on his shoulders.

In addition to deciding on the third presidential bid of the former mayor of Mexico City, an electorate that has become increasingly angry with the political status quo will also select 500 members of Congress and 128 senators.
"I hesitate to say that all of Lopez Obrador's support comes from simply an outrage vote," said Michael Lettieri, a Mexico scholar and research fellow at the Washington DC-based Council on Hemispheric Affairs think tank.
Front-runner Manuel Lopez Obrador
"Certainly it's an outrage vote and maybe this is concentrated in more urban intellectuals, but there's also a hope vote. There's a vote for Lopez Obrador that's because there's optimism that there can be change."
    Here's what you need to know about the largest election in Mexico's history, with more than 3,000 posts at stake:

    Who are the other leading presidential candidates?

    Presidential candidate Ricardo Anaya greets  supporters during an April rally in the state of Jalisco.