Leftist leader Andres Manuel Lopez Obrador called Monday for a "great national assembly" next weekend in Mexico City to show the government that the people oppose its planned tax reforms.
The rally will start at 10:00 a.m. next Sunday in the Zocalo, Mexico City's largest plaza.
"There is much unease in many sectors" over the tax reform package because it would "almost destroy the middle class," Lopez Obrador said in a radio message released by his political organization.
The tax reform package was approved last week by the lower house of Congress and is now awaiting debate in the Senate.
Lopez Obrador is the leader of the leftist National Regeneration Movement, or Morena, which is holding a series of meetings across Mexico as part of the process to become a registered political party.
President Enrique Peña Nieto is pushing to reform Mexico's tax system and energy industry, with his proposals drawing the opposition of the left.
Peña Nieto, of the Institutional Revolutionary Party, or PRI, won the 2012 presidential election with 38.21 percent of the vote, while Lopez Obrador took second place with 31.59 percent. EFE