The worse may be yet to come as a meeting is scheduled for Friday to plan the next move, with dissident union members pushing for an open-ended general strike to begin on Monday.

Disgruntled workers started early Wednesday morning, occupying various ISSSTE installations, forcing the cancellation of classes at the National Autonomous University (UNAM) and other learning centers, occupying the toll booths at the beginning of the Mexico City-Cuernavaca highway, and snarling traffic at strategic intersections throughout the city.

The demonstrations picked up steam as the day went on. By 6 p.m., some 7,000 marchers, predominantly education workers, were making their way to the city´s main square, closing off parts of Paseo de la Reforma and the Juárez/Madero corridor that feeds into the Historic Center.

The marchers also halted circulation of the Metrobus system as they filled past Insurgentes Ave. on their way to the Zócalo.

Similar demonstrations took place Wednesday across the nation, including the states of Chiapas, Oaxaca, Morelos, México, Guerrero, Colima, Querétaro, Michoacán and Zacatecas.

The main participants in Wednesday´s protests were teachers affiliated with the CNTE, a non-conformist wing of the national education workers union, known as the SNTE.

Also active were workers from the Mexico City government, the major public universities (UNAM, UAM and IPN), the private sector social security system (IMSS and its public sector equivalent, ISSSTE).

Government cultural workers from the National Anthropology and History Institute (INAH) and the National Arts and Culture Council (Conaculta) joined the marches as well.

A number of independent unions participated, under the umbrella organization UNT, as did campesino and civic groups.

Public employee workers were the most heavily represented in Wednesday´s actions, because recent reforms to their social security system, ISSSTE, precipitated the protests.

Earlier this year, the Calderón administration successfully shepherded legislation through both houses of Congress that phases in private retirement accounts for public sector workers, and significantly raises the retirement eligibility age for incoming workers.

The administration, and its National Action Party and Institutional Revolutionary Party allies in Congress, argue that the reforms were necessary to save the system from bankruptcy.

The unions, however, claim the new law will reduce retirement benefits and lead to a total privatization of ISSSTE, ending nearly a half century of "solidarity" retirement financing in which younger workers pay for their elders´ pensions before claiming theirs down the road.

Adding to the workers´ discontent is their conviction that the new law was imposed with no chance for input.

"The workers feel the law was approved without sufficient discussion, and they´re the ones assuming all the risk," said political analyst Fernanda Somuano, of the Colegio de México. "But I don´t see any interest on their part in destabilizing (the nation)."

Frustrated commuters might disagree, and protest leaders said Wednesday´s actions were just the beginning of a campaign to get the ISSSTE law repealed.