For as long as they can remember, Mexicans have heard presidential candidates promise to rid their country of the endemic corruption which is as much a part of Mexican life as the corn tortilla.
But once in office, the promise has too often been forgotten. Now, in Miguel de la Madrid Hurtado, Mexico appears to have a president who not only made anticorruption a major theme of his campaign but also appears determined to do something about the problem.
In his first 45 days in office, Mr. de la Madrid has:
* Set up the post of controller general to serve as a watchdog office over government spending, a sort of ''anticorruption ministry.'' Named to head the office is Francisco Rojas, a close de la Madrid associate who has a reputation for honesty.
* Ordered both elected and appointed officials to issue financial disclosure statements upon taking office, threatening perjury prosecution if the statements are later found to have been inaccurate.
* Begun the preparation of legislation that will make it a crime to enrich oneself while in public office.
* Abolished Mexico City police's notorious Investigative Division for the Prevention of Delinquency, commonly known as the ''secret police,'' whose 1,500 agents have been widely accused of abuses and corruption, as well as torture.
* Told Petroleos Mexicanos (PEMEX), the state oil enterprise, to investigate charges that at least one of its officials received a $342,000 bribe from a United States corporation.
''This is only the beginning,'' says a de la Madrid associate, adding that the new President ''is determined to get at the roots of corruption and to begin ferreting out wrongdoers.''
No one expects the task to be easy, least of all Mr. de la Madrid, but he made so much of the anticorruption theme during his campaign for the presidency that he ''now has to deliver,'' as the Mexico City daily El Universal said this month. There is, however, a great deal of public cynicism in Mexico about the issue.
After all, other presidential candidates have promised to go after corruption , only to forget the promise once in office. Mexicans, therefore, can perhaps be excused if they are a bit skeptical about Mr. de la Madrid's promises on the corruption issue.
Mexicans, for example, are watching closely how he deals with his predecessor , Jose Lopez Portillo, widely regarded as one of the most corrupt officials in Mexican history.
''I'm waiting until he makes a public spectacle of the Lopez Portillo corruption to know that he really means business on corruption,'' says a Mexican newspaper columnist who adds: ''If he gets up in Zocalo (the central plaza in Mexico City) and accuses Lopez Portillo of corruption, I'll be convinced.''
''Corruption,'' says Armando Ayala Anguiano, editor of Contenido, one of Mexico's most popular magazines, ''is Mexico's No. l problem.''
Mr. Ayala has been most outspoken on the issue, arguing that Mr. de la Madrid has an opportunity to ''change the pattern'' of Mexican life once and for all. So far, he gives the President good marks - as do most Mexican commentators.
But it is still too early to tell whether he actually will be able to carry out his promises.
He is going slow on looking into the murky past, in part at least because Mexican laws are not too clear on some aspects of corruption.
His attitude on PEMEX bribe charges, however, suggests that he may indeed go after past corruption. He has ordered an initial probe into allegations that numerous PEMEX officials accepted bribes from US firms during the Lopez Portillo presidency. To some, this signals a determination by Mr. de la Madrid to dig into the past. He has not given any hints about whether he will go deeply into the former President's own activities.