Mexican President Ernesto Zedillo, a lame duck entering the last year of his administration, told Mexicans tonight that his exit will mark a dramatic turning point in the nation's politics.

Characterizing the presidential transitions of the last quarter-century as economically chaotic because of what he labeled "irresponsibility, demagoguery [and] populism," Zedillo said in his fifth state of the union address that new election reforms and economic policies will ensure that "as we pass from the 20th century to the third millennium, we Mexicans will at last regard Mexico as an indisputably democratic nation."

But in a raucous reflection of the unprecedented campaign underway to replace Zedillo, the address erupted into a vitriolic display of partisan politics. Opposition members shouted and waved banners on issues that ranged from demanding Zedillo's resignation to ordering the removal of the army from the troubled southern state of Chiapas. In response, ruling party members nearly drowned out the rebuttal by the president of the lower house as he criticized Zedillo for putting a far too optimistic spin on conditions in a country where tens of thousands of people continue to live in extreme poverty.

In his address before the Mexican Congress, Zedillo delivered a dry but upbeat assessment of his administration. Tight economic policies have restored foreign investor confidence, tamed inflation, curbed deficit spending, spurred economic growth and restored the peso's stability following a devaluation in 1994.

In addition, democratic reforms have brought a series of elections that have been among the cleanest ever.

But most Mexicans say their standard of living has not recovered from the 1994 currency crisis. Crime remains a threat. The country remains the major transit point for illegal drugs into the United States, and corruption undermines the most important institutions.

Zedillo conceded that his administration has been unable to restore public confidence in a government long tarred by corruption, saying, "The impunity of individuals who break the law continues to be a painful aspect of our reality."

Nonetheless, Zedillo has a high approval rating. Although many Mexicans view him as a lackluster leader, 66 percent of the people questioned in a poll released today by the daily newspaper Reforma said they believe he is doing a good job of running the country.

Fewer than one-third of those polled believe Zedillo is handling the economy well, only 9 percent say he done enough to combat drug trafficking and a mere 7 percent say he has had any success in resolving the Chiapas conflict. But the president seems to have restored some trust to the tarnished office of the presidency.

For the first time in the ruling Institutional Revolutionary Party's (PRI) history, it will hold a primary Nov. 7 to select its presidential candidate rather than permit the incumbent to choose him, a reform initiated by Zedillo. That has led to internecine battles and has opened the door to powerful rivals from opposition parties, threatening to loosen the grip the PRI has held on the presidency for 70 years.