Accidental Candidate Leads Ruling Party From Tragedy to Victory Stands for PM-Mexico-Zedillo listed on PMs Digest. With PM-Mexico-Election, Bjt

MEXICO CITY (AP) _ Ernesto Zedillo wasn't meant to be the presidential candidate of Mexico's ruling party. But two shots from a revolver changed history, and today he declared victory in the country's elections.

Zedillo was the bespectacled and unassuming campaign manager of the Institutional Revolutionary Party's original candidate, Luis Donaldo Colosio, when Colosio was slain by a factory worker in Tijuana on March 23.

Zedillo, 42, who had never run for office, was picked to fill the shoes of the charismatic Colosio.

His resume included undistinguished stints as budget secretary and education secretary under President Carlos Salinas de Gortari. But he had the backing of the ruling party, which had won every presidential vote since its 1929 founding, often in elections tainted by fraud.

Still, he will go down as the first party candidate in history who wasn't a shoo-in. The party, known as the PRI, had been pressured to adopt election reforms under the gun of Indian guerrillas who made democracy a central demand of their January rebellion.

Zedillo has vowed to continue the economic reforms of his predecessor, who sold off hundreds of inefficient state enterprises, tamed hyperinflation and slashed Mexico's foreign debt burden.

Schooled in economics at Yale, Zedillo will preside over continuing implementation of the North American Free Trade Agreement, launched Jan. 1 with Canada and the United States. The pact will eliminate most trade barriers among the three countries over 15 years.

He is a bookworm who made straight As from elementary school through college. But during his campaign, he shrewdly played up his working class roots.

The son of a struggling electrician, Zedillo was born in Mexicali and raised in a poor neighborhood just yards from the California border, working as a shoeshine boy. He never forgot his humble beginnings, and his campaign slogan, ''Well-being for Your Family,'' reflected that.

Zedillo, who marched with considerably longer hair in anti-government student protests in 1968, today appealed for unity as he claimed his presidential victory.

''On this election day, there are no defeated. The most important victory is for democracy in Mexico,'' he said. ''We all have a place in that.''