STORY: Lopez Obrador, who put the plan forward in April, has long criticized the country's electoral authorities, including accusing them of helping to manufacture his defeats when he ran for the presidency in 2006 and 2012.
Lopez Obrador has said that the reform would let citizens elect electoral authorities and reduce the influence of economic interests in politics. It would also cut financing for political parties and limit advertising time.
Last week, Congress started discussing the plan. It sparked widespread concerns that the changes could presage a power grab because the plan gives the president more control over the electoral systems.
“We are here against the electoral reform that Morena party is proposing to destroy the Mexican democracy to lead us to places such as Venezuela and Cuba,” protestor Enrique Anaya told Reuters. A Reuters witness estimated tens of thousands protesters had taken part while a police officer on Reforma who witnessed the march estimated 50,000.
In the past, Lopez Obrador pursued contentious policies by pitching referendums - including on the cancellation of a part-built airport - to claim popular mandates for his objectives.