The millionaire president, who retains vast business interests but swears by arrangements aimed at avoiding conflicts of interests, faced widening revolt this week after increasing numbers of labor union members and teachers threw their support behind students.
A central union of workers added to general calls for education reforms a longer list of changes, which includes a redrafting of the constitution and statutes to remove what critics see as vestiges of the past military dictatorial regimes, notably the highly controversial rule of Gen. Augusto Pinochet from 1973-90.
The Unitary Central for Workers called for a nationwide strike for the second consecutive day Thursday and invited other unions to join the protest action.
Student protests against high tuition fees began about two months ago and focused on private academic institutions operating with impunity, alleged corruption and favoritism in the education system.
Protest leaders said they hoped to make the rallies "the biggest national strike of the last decade." It is the first 48-hour national strike since the Pinochet dictatorship.