By GINGER THOMPSON
 
MEXICO CITY, Aug. 31 - President Vicente Fox said in an interview on Tuesday that if Mexico's Supreme Court would not hear the genocide charges his government had filed against former President Luis Echeverría, he would call for the creation of a truth commission to investigate abuses committed by the Institutional Revolutionary Party, which used fraud and corruption to rule the country for more than seven decades.

In July, a special prosecutor appointed by Mr. Fox made history in asking a court to order the arrest of Mr. Echeverría, two of Mr. Echeverría's former aides and three military generals for the killings of student protesters in 1971. It was the first time such a case had been brought against a former president in Mexico, and was considered a test of Mr. Fox's resolve to punish those responsible for the old government's worst abuses and to establish the rule of law.

The court threw out the charges the next day, and with them threw one of Mr. Fox's most important political projects into disarray. The government then sent the case for review by the Supreme Court.

"I expect that the opinion of the court will establish who is responsible and determine whether the statute of limitations has passed,'' said Mr. Fox, the first president elected from an opposition party. "If the court does not get to the bottom of the matter, I will convene those civic groups working with the special prosecutor, who have a full understanding of the case, to issue their own verdict, a historic verdict in the form of a truth commission.''

He added, "It would not be a judicial body, but a citizen's group that would conduct a trial and make clear for history who was responsible.''

Mr. Fox spoke on the eve of his annual state of the union address, which symbolically marks the end of the fourth year of his six-year term. His stunning election in July 2000, ending the PRI's hold on the presidency, was fueled by a national tidal wave of optimism and hope for broad changes. Since then, however, political and economic forces have hit hard against him. A recession in the United States cost Mexico hundreds of thousands of jobs. A bitterly divided Congress, led by the PRI, rejected important tax and energy reforms.

His critics charge that the Fox government has failed to dismantle the political system that robbed and repressed this country for most of the last century. Rather than change, they say, it has delivered more of the same.

Optimism has turned to scathing disappointment. Some 50,000 union members and farmers marched against Mr. Fox on Tuesday. Organizers said that on Wednesday demonstrators plan to block roads and border crossings, walk off their jobs and march on Congress, where Mr. Fox is scheduled to give his speech.

With the press and political classes focused on 2006, there are many who see Mr. Fox as a lame duck struggling to secure his legacy.

In the interview on Tuesday, President Fox rejected that image, with upbeat, at times defiant, responses.

"Certainly there is a disparity between the perceptions of the people, the expectations they have of change and the progress we have made,'' Mr. Fox said. Asked if there was anything that had disappointed him, he replied: "No. Absolutely nothing.''

"If anyone understands clearly what can be accomplished in six years, it is me,'' he said. "There is no gap between my expectations and achievements. I am at peace and very satisfied.''

President Fox said that in his address on Wednesday he would tell Mexico that times had been hard, but there was reason to be optimistic. He said that the once stagnant economy would grow by 4 percent this year and that the country had begun to recover lost jobs. He said that in the last two years the number of people living in poverty had begun to decline and that the government had built about 1.4 million houses for low-income families.

Mr. Fox said he still hoped to get some kind of tax and energy reforms through Congress. But he said the priorities for his last two years in office would be to maintain economic growth, expand basic medical insurance to all Mexicans and install blackboards and computers in all fifth- and sixth-grade classrooms.

"I believe that would be a real education revolution,'' he said.

Four years ago, however, Mr. Fox helped set this country's sights much higher and Mexicans say they want more from him than new roads and houses.

Voters had expected that the Fox government would tear apart Mexico's corrupt and authoritarian political system and rebuild it from scratch, said Peter Hakim of the Inter-American Dialogue in Washington. "He got over the hurdle of getting into office on the presumption that there would be no backsliding, that the old system was dead and gone, that he had slain the dragon,'' Mr. Hakim said. "But he did not establish the ways and mechanisms of managing a democratic society.''

Meanwhile, the PRI seems headed toward a political comeback. In addition to the Congress, the party controls 17 of the country's 32 states. The PRI removed Mr. Fox's National Action Party, or PAN, from power in its former strongholds in the states of Nuevo León and Chihuahua. And it won important mayoral victories in the cities of Tijuana and Ciudad Juárez.

Offering a rebuttal of Mr. Fox's speech Wednesday night will be a PRI congressman, Manlio Fabio Beltrones, a former governor of Sonora whom American officials once accused of having links to drug-trafficking.

In the 40-minute interview Tuesday, Mr. Fox discussed his decision to invite the PRI to join him in a so-called "joint transition.'' It is a strategy, critics charge, that helped revive the PRI, rather than weaken it.

"I did not contemplate in this joint transition the destruction of anyone, much less attacks against political parties, but the start of a process of change toward a new democratic culture,'' Mr. Fox said.

The president said that his was a minority government and that he had little choice but to work with his adversaries to win support for reforms. Clearly that strategy failed. The PRI has used its seats in Congress to regain national power. Mr. Fox did not disagree. Nor did he apologize.

"There are many people in Mexico and in the world that still long for, or feel nostalgia, for authoritarian government,'' he said. Referring to the Aztecs, he said, "Mexico, in particular, that was the culture - the culture of the Tlatoani, the culture of authoritarian acts.''

Breaking with those traditions, Mr. Fox said, "is exactly the cause I lead.''

When asked why he had forced no changes in the leadership of the nation's largest unions, which uphold the PRI's vast systems of patronage, he said: "That is not my responsibility. They will have to look inside their own organizations and determine their own process of change and democratization.''

Lorenzo Meyer, a historian, lamented in an interview that Mr. Fox will probably go down in history as the man who defeated one of the world's longest ruling political parties, then helped it return to power.

Again, no apologies from the president.

"The people will elect those who they believe should be the president of the republic, and there is no reason to make predictions,'' he said. "The election will be democratic and Mexicans will chose who they want to continue governing the country.''