When that is not enough to ensure a PRI victory, opposition leaders say, the government will stuff the ballot boxes, falsify voter registrations or even change the final tally.

Government officials say the charges are unfair, but they admit to having a credibility problem both at home and abroad. So Mexican President Miguel de la Madrid announced last summer that he would propose sweeping changes in election system.

This morning his suggestions were presented to the Mexican Congress. Some of the proposals satisfy long standing demands of the opposition. The most important may be the introduction of the translucent ballot boxes so that official poll watchers can verify that no one has stuffed the boxed beforehand.

A new federal elections commission will be established with the power to judge the fairness of elections and a permanent list of voters would be prepared with the assistance of all political parties.

The reforms would also give opposition parties more representations in the national Congress. 200 out of 500 congressional seats will be awarded to opposition parties in proportion to the number of votes they receive.

It's the most ambitious political reform in recent Mexican history but opposition leaders here are still not satisfied. Sisrial Romaro, a Congress woman from the National Action Party says, no real reform is possible in Mexico until the bond between the government and its official party, the PRI, is broken.

Opposition leaders today responded to the President's reform package by offering one of their own. They propose that all the seats in the national Congress be distributed in proportion to party votes. And they want the elections to be overseen by a separate tribunal completely independent of the government.

But the opposition's proposals have no chance of being approved since the PRI totally controls the National Congress and enacts virtually everything the government proposes. In Mexico City, I'm Tom Julton.