MEXICO CITY (Reuters) - Mexico's political parties will formally choose presidential candidates on Sunday, setting the stage for a race between a leftist holding a strong lead, a young leader of a right-left coalition catching up, and a trailing ruling party candidate.
With six weeks to go before campaigning begins for the July 1 vote, Andres Manuel Lopez Obrador, 64, will be named as candidate by the leftist Morena party he founded after his second failed bid for the presidency in 2012.
The former Mexico City mayor has held a double-digit lead in most polls since last year and his support grew in two surveys last week, but coalition candidate Ricardo Anaya, the youngest of the three at 38, narrowed the gap.
The ruling party's choice, former finance minister Jose Antonio Meade, 48, has been trailing far behind and losing support in recent polls as he struggles against public anger at the government over violence and corruption scandals.
"If this trend continues, the race will become more competitive between the two front runners," political risk analysts at Eurasia Group said in a note on Friday. "But voter intentions have historically shifted throughout the campaign season, so much could change."
Major parties will hold events on Sunday to formally nominate their candidates, though all three men were unopposed during the period set out for parties to decide on their picks.
Lopez Obrador has vowed to combat inequality and corruption without upsetting the macro-economic balance. Some international investors are concerned he could undermine decades of free-market reforms in Mexico.
Analysts have said Lopez Obrador could slow the pace of President Enrique Pena Nieto's opening of the state-run energy sector to private investment, but they expect he would face a divided Congress that would make any rapid shifts in policy unlikely.
Anaya resigned in December from his post as president of the center-right National Action Party (PAN) to pursue the presidency in an alliance with the center-left Party of the Democratic Revolution (PRD). His coalition backs a universal basic income program to fight poverty.
Frustration with corruption and a surge in murders under Pena Nieto has affected the credibility of Meade's promises to be tougher on graft.
The election will mark the first time independent candidates can run for the presidency. Margarita Zavala, wife of former President Felipe Calderon from the PAN, and Jaime Rodriguez Calderon, who became Mexico's first independent governor in 2015, are expected to get enough signatures to run.
Analysts doubt any of the potential independent candidates have a chance, but their supporters could be a factor to the outcome in a close race.
(Reporting by Diego Ore and Michael O'Boyle; Editing by Frank Jack Daniel and Leslie Adler)