MEXICO CITY (Reuters) - Mexico City Mayor Marcelo Ebrard is trying to rally Mexico's left behind him after rival Andres Manuel Lopez Obrador said he would break with the established parties following his defeat in July's presidential election.
Lopez Obrador led a three-party leftist alliance to second place in the election, but on Sunday he told a massive crowd in Mexico City he would form a new political group, potentially opening up a serious rift in the left.
In an interview with Reuters, Ebrard said on Thursday he aims to bring the left back together, contrasting himself with Lopez Obrador, who has strong support among the poor and came close to winning the last two elections but alienated centrist voters with his combative style.
Lopez Obrador staged massive, disruptive protests in the capital to contest his narrow presidential loss to Felipe Calderon in 2006 and this time around he is refusing to accept defeat to President-elect Enrique Pena Nieto.
By going solo with a new party, Lopez Obrador has laid bare tensions in the left between moderates ready to work in Congress and accept Pena Nieto's win, and those firmly opposed to cooperating with his Institutional Revolutionary Party (PRI).
Lopez Obrador's decision was "utterly predictable" and had not helped the cause, Ebrard said, noting it would be "absurd" if the left did not run on a joint ticket in future elections.
"What we must avoid is having the left destroy itself, that we lose votes next year, that we're no longer second strongest force in 2015 (when legislative elections are held)," said Ebrard, 52, who plans to run for the presidency in 2018.
The rivalry between moderates like Ebrard and hardliners who back Lopez Obrador has become a test of whether Mexico's left can set aside its differences to finally win the presidency in Latin America's second-biggest economy, where around half the population lives in poverty.
Ebrard's Party of the Democratic Revolution (PRD) is by far the biggest of the three leftist parties in Congress, and he promised to lead a forceful and unified opposition to the PRI and its economic reform agenda under Pena Nieto.
But with the PRD alone boasting six identifiable factions, Ebrard, who will not have a seat in Congress when he leaves office in December, faces an uphill struggle.
"The job I have to do is make sure these different factions, groupings or parties are united for the elections, because if we don't achieve this before 2018 you're not going to gather the strength needed to be a national alternative," he said.
Educated in Mexico and France, the urbane Ebrard made a name for himself by reducing violent crime in the once notoriously dangerous capital while chief of police under Lopez Obrador, who was mayor between 2000 and 2005.
As mayor, Ebrard won praise from the left with laws that legalized abortion and gay marriage in the city, while continued progress on security issues and infrastructure projects have won him support among political moderates.
Ebrard lost out to Lopez Obrador seeking the left's presidential nomination this year, and he acknowledged on Thursday that the rivalry with his former mentor could be a problem.
If the two did not avoid a "permanent conflict," it would play into the PRI's hands - and blunt the left's role as the "shadow cabinet" in the next government, Ebrard said.
The left, he added, needs to be a counterweight to efforts by the PRI and the conservative National Action Party (PAN) of outgoing president Calderon to pass economic reforms.
Pena Nieto, who takes office on December 1, has pinned his hopes for stronger economic growth to three main proposals: opening up state oil monopoly Pemex to more private investment, softening Mexico's labour laws and expanding the tax base to boost government revenues.
These plans all needed to be opposed, Ebrard said, noting that if the PRI won over the PAN for its reforms and failed to boost growth, the left ought to be able to capitalize.
"If we start to approve things with them, we're going to be the last wagon on Mexico's conservative train," Ebrard added. "This is not being an opposition."
Editing by Kieran Murray and Cynthia Osterman