MEXICO CITY — FOR more than six decades, Mexico's Institutional Revolutionary Party, or PRI, has kept a firm grip on power.The question hanging over this Sunday's federal legislative and state gubernatorial elections in Mexico is not whether the PRI will win again, analysts say, but whether these will be viewed as fraud-free victories. An affirmative answer is important to President Carlos Salinas de Gortari, who is trying to shake Peruvian poet Mario Vargas Llosa's characterization of PRI's lock on power as the "perfect dictatorship." After winning the 1988 presidential election by a narrow margin (amid charges of fraud), Mr. Salinas has thrown himself into rebuilding both the PRI political machine and the credibility of the electoral process. These elections are the first test of Salinas's "democratic" reforms. "This is a chance for Salinas to legitimize his domestic and external image," says Jacqueline Peschard, a political scientist at Universidad National Autonoma de Mexico (UNAM). "He arrived with an image of questionable legitimacy. And to guarantee passage of the free-trade agreement, the North Americans need to see an honest election." To that end, Salinas has pushed through tougher penalties for electoral fraud, set up a new voter roll, created a permanent, relatively independent electoral commission that includes oversight from major political parties. "On balance, the reforms have been positive," says Luis de la Garza, head of the UNAM political science department. "To steal a victory, the PRI will have to use more sophisticated means than in the past. Stuffing ballots, filling the rolls with dead voters, and robbing the voting urns won't be effective anymore." But not all the reforms are advances, Ms. Peschard says. New rules, for example, give an automatic majority in the legislature's lower house to the party that wins more than 35 percent of the votes, she says. "It's an injustice which gives the PRI - if it wins - an extra advantage." And the new Federal Electoral Institute already had become embroiled in a controversy over slow distribution of voter credentials. Opposition parties tried to postpone elections, claiming the PRI was orchestrating delay to prevent proper review of voter lists before the elections. IFE officials called the holdup an administrative problem. Ultimately, 92 percent of voter cards were distributed. Some IFE employees claimed extra voter cards were given to the PRI, so theoretically an imposter could vote twic e. Not that fraud appears to be necessary. Polls predict the PRI will steamroll the opposition. The PRI could even win back the majority it lost in the legislature in 1988. The only close races are likely to be for governorships in San Luis Potosi and Guanajuato states, and the legislative seats for Mexico City's federal district. These races will be scrutinized by about 500 Mexican election observers. In the name of sovereignty, the government refuses to accredit international observers. Among the contests, the Mexico City race will be the most significant, says Denise Dresser, a political analyst with Grupo de Economistas and Asociados, a private consulting firm. Long a PRI bastion, the ruling party in 1988 received a crushing defeat in Mexico City. But Ms. Dresser predicts a major PRI victory this time in the federal district, exemplifying the shift in political winds throughout Mexico. "This is the political pulse of the nation, the center of power," Dresser says. "The [left-leaning] Party of the Democratic Revolution [PRD] will lose big here. The PRD has become fragmented, weakened, a nonactor over the past two-and-a-half years." PRI officials credit their resurgence to democratic reforms in the party that have produced better candidates, and they cite economic achievements by Salinas. Voters, they say, have noticed the drop in inflation, the nation's debt restructuring, and the third year of economic growth. Dresser, however, attributes the PRI's revival to other factors. "The opposition lacks the same resources and media exposure of the PRI. And, no other party has Pronasol. Salinas has effectively stolen the support away from the left with Pronasol," she says. Pronasol, the government's high profile $3.5 billion health and public-works program, is aimed at improving the lot of the half of Mexico's population living in poverty. While Salinas privatizes state corporations and cuts the federal budget, "Pronasol repositions the PRI as a welfare machine," Dresser says. What worries Dresser is that these elections could mark the end of democratic reforms in Mexico. "If the PRI wins massively and the opposition is so weakened, what motivates the PRI to reform further?"