Mexico's presidential front-runner Enrique Pena Nieto holds a wide lead heading into Sunday's election, putting the once-dominant Institutional Revolutionary Party (PRI) on track to regain power.
Here are profiles of the main candidates:
Backed by his good looks, powerful connections and the strongest political machinery in the country, Enrique Pena Nieto has led polls in the race to win the Mexican presidency for more than 2 1/2 years even though he only formally became a candidate a few months ago.
Still in his twenties when the PRI last won a presidential election in 1994, Pena Nieto is the telegenic new face of a party that dominated Mexico, sometimes ruthlessly, for most of the 20th century.
The 45-year-old former governor of the State of Mexico is widely expected to win the election on Sunday. He has pledged to reduce drug-fueled violence and create more and better jobs for the growing population.
A trained lawyer with influential relations within the PRI, the impeccably groomed Pena Nieto has held a double-digit lead for nearly the whole campaign despite revelations that might have derailed his bid in other countries.
In January, he admitted cheating on his first wife and fathering two children out of wedlock with different women, an indiscretion that had little impact on his ratings.
He drew more scorn for struggling at a book fair to name three books that had influenced him, and his close ties with Mexico's dominant broadcaster Televisa drew a wave of youth protests against him towards the end of the race.
But Pena Nieto rode out the storm and most polls suggest he will win over 40 percent of the vote against his two main rivals, returning the PRI to power for the first time since its 71-year rule was ended in a 2000 election by the conservative National Action Party (PAN).
Promising a "democracy of better results" and higher living standards, Pena Nieto has sought to sell the message that the PRI is the natural party of government, the only one equipped to deal with Mexico's problems.
His popularity has helped to make the PRI electable again for Mexicans who remember the party for corruption scandals, vote-rigging and repression of dissent.
Pena Nieto is adamant that this time will be different.
"This is a party reborn, ready to win the democratic contest. But above all, ready to govern democratically, with complete transparency and accountability," he said last month.
A relative unknown in 2005 when he won the governorship of Mexico's most populous state as a protege of his relative, previous governor Arturo Montiel, Pena Nieto slowly took a hold of the PRI as the party saw him as its ticket back to power.
He was seen as an effective state governor, significantly increasing infrastructure spending during his tenure.
He has a cozy relationship with Mexico's most powerful broadcaster Televisa. His first wife died in 2007, and his fame grew when he married a popular soap opera actress in 2010.
Aides describe the immaculately turned out Pena Nieto as a pragmatist unafraid of making tough decisions and he worked well with opposition parties when he was governor.
Critics say his popularity owes much to the support of entrenched business interests in Mexico, and that the need to return the favors could weaken his presidency.
Charismatic leftist challenger
The charismatic leftist Andres Manuel Lopez Obrador jolted markets as he narrowed in on Pena Nieto during second half of the campaign, but he is expected to finish second as he did in 2006, this time trailing by a far bigger margin.
Often referred to "Peje" -- a type of tough swamp fish in his native state of Tabasco -- Lopez Obrador is renowned for leading supporters on huge protest marches and making impassioned speeches condemning Mexico's powerful oligarchs.
He has revived fears of fresh protests by accusing the PRI of planning to rig the vote, though losing by a wide margin would undermine any calls for demonstrations.
Lopez Obrador has vowed to create 7 million new jobs and grow the economy by 6 percent a year if elected.
While open to modernizing state-owned oil giant Pemex, he is against partial foreign ownership. He also pledges to wind down the army's role in the drug war.
Lopez Obrador began his career working with indigenous people in his home state before helping to found the Party of the Democratic Revolution (PRD) in 1988.
As mayor of Mexico City from 2000 to 2005, Lopez Obrador built a loyal base by establishing social welfare programs and infrastructure projects.
But critics say the PRD candidate, who appears older than his 58 years, is hot-headed and undemocratic.
This stems, in part, from his failed 2006 bid. After losing the election by a whisker, he claimed the vote was rigged and called supporters out in protest, clogging parts of the capital for months. It was a protest campaign that alienated some voters and failed to prevent Felipe Calderon from taking office.
Lopez Obrador has been less confrontational in this election campaign, reaching out to business leaders and preaching a message of love and understanding.
He has nonetheless failed to dent Pena Nieto's double digit lead in most polls after indifferent showings in televised debates and interviews.
Would-be first female president
Mexico's ruling conservatives pinned their hopes on a career politician to become the country's first female president, but internal divisions and dissatisfaction with the government's record have undermined Josefina Vazquez Mota's bid.
Trailing in third place in most polls, her hopes have steadily faded. The petite 51-year-old campaigned on a pledge to continue Calderon's policies. She also played up the gender card to woo female voters she calls "warriors," and has promised to look out for families.
She won support from grassroots voters in the PAN and beat out Calderon's perceived favorite -- former finance minister Ernesto Cordero -- in a February primary vote.
Seeking to show dynamism, she gave interviews on the campaign trail while exercising on a training machine in the gym. But as her campaign faltered, she showed signs of strain. At one rally speech she had to sit down after feeling faint.
As a federal deputy, Vazquez Mota -- who became her party's leader in the lower house of Congress -- vigorously backed Calderon's reforms, but her efforts to see them through the legislative process often foundered on opposition from the PRI.
This did not deter her from setting out ambitious policies during the campaign, such as listing up to 49 percent of state oil firm Pemex on the stock exchange.
But backing the government's drug war strategy has proved a liability due to discontent over the violence. More than 55,000 people have been killed since Calderon deployed the army against drug cartels after taking office at the end of 2006.
Vazquez Mota, a former education minister, extols her role as a mother of three daughters in a 27-year-long marriage.
Courting female voters, she promotes the cause of women's health and education. Her proposals include lengthening Mexico's short school day so mothers have more time to work.
Hoping for votes from the PAN's strong Roman Catholic base, she opposes abortion but she also opposes jailing women for terminating pregnancies, a practice in some of Mexico's states.