Chnages to Mexico's labor laws passed in Congress and to be signed by president Calderon include companies having to pay only one year of back wages to laidoff workers for lawsuits on unfair dismissals. The law also formalized part-time work and temproary training contracts. The effort is likely to foster greater formalization of the workforce and push fewer workers into the underground economy. About 29% of Mexican workers are in the underground economy, where worker protections and legal benefits are lacking. Also made part of the law an yearly audit of union finances and election by secret ballot for unions. Mexico's large public sectors form a core base for support of the newly elected PRI government.