Front-runner wants to debate legalizing drugs

Andres Manuel Lopez Obrador, a fiery former Mexico City mayor, made the proposal at a "dialogue on peace and justice" that was also attended by his main rivals, conservative Ricardo Anaya and ruling party candidate Jose Antonio Meade.

Security has emerged as perhaps the biggest issue in the July 1 election, after Mexico registered a record 25,000 murders last year.

Violent crime has exploded since the government deployed the military to fight the country's powerful drug cartels in 2006. Since then, Mexico has registered more than 200,000 homicides.

"Legalizing drugs is a subject that must be debated," said Lopez Obrador.

"Why not talk about it? And why not -- if it's what's best for the country -- approve it and implement it, listening to everyone's input?"

Anaya and Meade were more cautious, endorsing a debate on legalizing only marijuana.

"I don't believe legalization would lead to a reduction in violence in the short term," said Anaya, a former speaker of Congress.

Meade, a former minister running for deeply unpopular President Enrique Pena Nieto's party, meanwhile acknowledged Mexicans' frustration with a justice system that fails to punish more than 90 percent of violent crimes.

"Our biggest failure, and the area we most need to reform... is related to the impunity that reigns in Mexico today," he said.

Lopez Obrador, who has a double-digit lead over his rivals in opinion polls, did not mention another controversial proposal of his: an amnesty for criminals convicted of drug crimes.

Mexico has gradually loosened its drug laws, legalizing medical marijuana last year and allowing recreational pot users to carry up to five grams.

But the country has been deeply destabilized as its cartels have risen to become the most prominent suppliers of hard drugs such as cocaine and heroin, to the United States.