A long-delayed vote count is slowly trickling out of election headquarters in Mexico this week, showing PRI presidential candidate Carlos Salinas de Gortari with a hefty 52.9 percent of the vote. But the nearly week-long lapse in reporting election results has caused significant harm to the PRI-dominated government, already suspected of vote fraud.

If the Salinas lead holds up, and there is no reason to suspect it won't, the PRI will continue its 59-year dominance of Mexico presidential and Senate races. Yet there is a difference this time.Runners-up in the presidential balloting were Chauhtemoc Cardenas, a leftist candidate with 29.1 percent of the vote, and conservative Manuel Clouthier with 16.8 percent.

This means that the lead compiled by Salinas is 20 points lower than any other candidate in PRI's long control of Mexican government. In addition, the PRI's one-party stranglehold in state and Senate elections appears to have been broken by the loss of important offices.

All of this would have been welcome last week as a sign of democracy at work, of the end of one-party rule. But the delay in counting returns - blamed on the breakdown of a computer - has cast clouds of doubt over the results. Charges of fraud in previous elections had already made opposition parties suspicious of government tinkering, and the week-long delay in released vote results has only reinforced those suspicions.

There are grounds for fearing fraud. For example, in hundreds of voting booths, the PRI won every single vote. The percentage of reported non-voters is unusually high - 53 percent. In 1982, in a less-emotional election, only 30 percent failed to cast ballots.

Opposition candidates, and their growing political parties, may refuse to accept the vote tally and cause trouble. The odds are that the governing party will keep control. But the suspicion of fraud, a national economy that is in trouble, and sharply reduced living standards could mean serious unrest.

Whatever happens, the U.S. will have to keep a careful eye south of the border. It's clear that Mexico is in for change and upheaval. That change may be welcome and give the people of Mexico new hope. Or it could turn nasty. A Mexico in turmoil would not be a welcome situation on the U.S. border.