Nearly half a million union teachers began a 24-hour nationwide strike Tuesday and about 200,000 teachers and other school workers marched in the nation's capital to demand their wages be doubled.

The educators also called for the dismissal of the National Education Workers Union's leadership, charging corruption and fraudulent union elections last month.Striking teachers allege leaders of the 1.8 million-member union, known by the Spanish-language acronym SNTE, represent the government's interests and not those of the teachers. They say many union leaders were officially "hand-picked."