By Bérengère Sim and Daina Beth Solomon
MEXICO CITY (Reuters) - Mexican President-elect Andres Manuel Lopez Obrador's party could face a $10 million (7.56 million pounds) fine for violations of campaign finance rules, the national electoral institute said on Wednesday following the group's wide-reaching election victory.
Lopez Obrador, a former Mexico City mayor who has vowed to root out corruption and make government contracts transparent, on Sunday won by a landslide while his leftist National Regeneration Movement (MORENA) took an outright majority in Congress.
The possible fine of more than 197 million pesos, slated to be put to a vote by the National Electoral Institute (INE) on July 18, would be the largest related to campaign financing for the recently concluded election season.
It is nearly as much as the 207.5 million pesos authorized by INE as MORENA's public financing for campaign spending in 2018 federal elections.
MORENA's representative at the institute did not immediately respond to a request for comment.
According to the institute, MORENA formed a trust that it did not report in which it deposited, mostly through cash deposits, about 78.8 million pesos ($4 million) as well as checks and bank transfers.
"The party actively participated in forming this financial instrument to collect resources as a financing method contrary to the rules," the INE said in a statement.
It said the estimate of a possible fine was based on omissions in MORENA's fiscal report as well as exceeding cash contribution limits and receiving funds from unknown persons and prohibited entities.
Two sources with knowledge of the matter said the trust under investigation was called "For the Others," set up by MORENA to help victims of devastating earthquakes last September.
The INE said about 64.4 million pesos ($3 million) was withdrawn from the trust, distributed in checks to party members and were cashed later.
The INE began its investigation after the ruling Institutional Revolutionary Party (PRI) filed a complaint accusing MORENA of launching the fund without reporting it to authorities.
INE said it is also considering fining the PRI 36.5 million pesos ($1.88 million) for deducting money from state workers in 2015 for the party's Chihuahua state treasury, and the National Action Party 3 million pesos ($154,337) for taking funds for the recently concluded federal elections from prohibited entities.
(Additional reporting by Lizbeth Diaz, Christine Murray and Michael O'Boyle; Editing by G Crosse, Robert Birsel)