Greece’s largest unions have called for a 48-hour general strike next week to protest a new austerity package that the nation’s parliament will vote on.

The General Confederation of Workers of Greece (GSEE), one of the country’s largest umbrella unions, told CNN the work stoppage will take place next Tuesday and Wednesday, concurrent with the Parliament’s vote of the budget measures.

Greece’s Prime Minister George Papandreou is under extreme pressure to get his austerity budget passed if he is to receive the last 12-billion euro tranche of the 110-billion euro bailout package the European Union and International Monetary Fund agreed to provide last year. The budget must also be approved if Greece is to receive a second, even larger, bailout from European authorities.

Also, without that last tranche, Greece could default on its debt by mid-July, an event that could be cataclysmic for European banks and the Euro Zone as a whole.

After the Greek parliament votes on the austerity package, EU finance ministers will meet on July 3 to consider the disbursement of the final tranche of last year’s bailout agreement.

Papandreou’s cabinet recently survived a confidence vote in Parliament, despite the fact that large swaths of the public are vociferously opposed to the austerity budget, which calls for, among other things, more tax hikes, job cuts, pension cuts, salary freezes and the privatization of many state assets.