MEXICO CITY — MEXICO CITY -- A lot of Mexicans say that Cuauhtemoc Cardenas Solorzano is the legitimate president of the country. Those who believe it say that it was the mysterious breakdown of computers counting the votes five years ago that enabled Carlos Salinas de Gortari to beat Mr. Cardenas and keep his Institutional Revolutionary Party (PRI) in office, just as election fraud, the state-controlled media and the brutal repression of opponents have kept the PRI in control of Mexico's government for 64 years. But five years later, Mr. Cardenas is back campaigning for president in next August's election. He won't be running against Mr. Salinas because a president is limited to one term. But he'll be running against the Salinas legacy and the memory of that 1988 election that he might have won, many believe, if it hadn't been rigged or if he had protested the results more forcefully. "We will begin the fight as soon as we see signs of political fraud," Mr. Cardenas, 59, said. "This time we will fight with the tools that the law gives us and I am sure that a strong demonstration of civil disobedience will put down this system of repression forever." The plain-spoken, left-of-center politician has been campaigning informally since June and accepted the presidential nomination of the Democratic Revolutionary Party (PRD) Sunday. As Mr. Cardenas speaks to business owners, farmers, teachers, union leaders, religious groups and students across the country, his message is marked by a singleness of purpose. "[Mr. Cardenas] clearly has a sense of crusade," said commentator Jorge Castaneda. "This is not a fight for the presidency," Mr. Cardenas had said in an interview. "This is a fight for democracy." Most of his speeches are short on alternatives for addressing Mexico's poverty and rising unemployment or for saving the country's failing farms and small industries. But Mr. Cardenas speaks passionately about establishing a government that responds to the demands of the people. He promises reforms to create a free press, a more independent Congress, free education at all levels and sweeping constitutional reforms. He tells people he knows how it feels to be cheated by the government. The message has considerable resonance. "The most important issue Mexico has not resolved is the establishment of real democracy," said Tomas Bourjes, a professor at the Autonomous University of Chapingo, an agricultural school. "[Mr. Cardenas] is the only candidate who can accomplish that goal. He has been constant in his fight." The PRI is showing signs of nervousness. Recently, Mr. Cardenas was a guest on a popular radio show of political commentator Miguel Angel Granados Chapa. Mr. Granados said the next day the heads of the station warned him to be careful about whom he interviewed. Mr. Granados said he was sure the "hostile" directive came from the government licensing agency and he quit. Two weeks ago, a campaign dinner in Veracruz was interrupted by a group of transvestites who reportedly hugged and kissed Mr. Cardenas. Local reporters said they had been notified by government officials that Mr. Cardenas would receive a "special endorsement." Photos of Mr. Cardenas with the transvestites then made the front pages of local newspapers. "They are afraid of my candidacy because they know how discontented Mexico is with their corruption and lack of democracy," Mr. Cardenas said. "But no matter what they do, I will be elected president in 1994." A product of the system Mr. Cardenas is a product of the system he is now trying to dismantle. His father, Lazaro Cardenas, was president of Mexico from 1934 to 1940 as well as a revolutionary general and remains one of the country's revered heroes, remembered for his concern for the depressed living conditions of the masses. He initiated social and agrarian reforms, promoted education in the rural areas and created the Confederation of Workers of Mexico, which is the country's largest labor federation. Cuauhtemoc Cardenas Solorzano, the president's only son, was just a toddler during those tumultuous times. But as he grew up, he and his father were very close and traveled together often. The elder Mr. Cardenas died in 1970. Many say his ideals live on through his son. An engineering graduate, Mr. Cardenas began to pursue a political career within the PRI. In 1980 he was elected governor of the central state of Michoacan. In 1987, he and a group of PRI members went up against the old guard and its time-honored practice of allowing the incumbent president to select his successor to lead the PRI and inevitably the country. They wanted a convention. Conservative PRI leaders refused. Mr. Cardenas and the others resigned from the party, and Mr. Cardenas announced his candidacy for president. He won enthusiastic support. But he wasn't surprised by how things turned out. "He knew there would be fraud," said longtime friend, historian Adolfo Gilly said. "He knows the regime from inside, and he knew they wouldn't let him take control of the government." Winning the same support will be more difficult in 1994. Mr. Salinas has won widespread domestic and international popularity and respect by implementing social and agrarian programs. This popularity could translate into popularity for the man he choses to succeed him. That decision, government officials say, will be made in January. Views on NAFTA Although Mr. Cardenas' campaign advisers say he is withholding most of his proposals for later in the campaign, the candidate has expressed opinions about one very big issue: the North American Free Trade Agreement. Mr. Cardenas has said he is not opposed to free trade with the United States, but is opposed to this agreement because it does not address the serious inequalities between the United States and Mexico, such as wage differences. And he supports more government investment in modernizing Mexican farms and industries so they can compete with U.S. farmers and manufacturers. While Mr. Cardenas remains popular, political analysts say he no longer inspires the same enthusiasm that he did in 1988. Mostly supported by the poor, Mr. Cardenas is working to overcome the fear among the middle and upper classes that he is a radical leftist who wants to return Mexico to its nationalistic, protectionist past. He has made an effort to meet with people generally unfriendly to his campaign, such as business leaders, religious groups and wealthy farmers. "Some businessmen who met with him said that he was a very serious man and that he had positive intentions," said Oscar Loza Ochoa, a human rights advocate in the northwest state of Sinaloa. "Still, they will vote for the PRI." But the candidate remains upbeat. "Even if they do not vote for me, we are winning," he said. "They are seeing that we have viable alternatives and that we are not going to shake Mexico off its feet."