AS President Clinton, in the words of the song, heads "south of the border down Mexico way" the mission bells are not yet ready to ring out a welcome. The President has a lot to do to assuage bruised Mexican feelings over recent US denunciations of corruption, drug trafficking, illegal immigration and even bad strawberry imports which caused food poisoning in some schools.

Mexican resentment towards the US was greatly stirred up earlier this year as Congress tried to reverse the President's decision to "certify" that Mexico was fully cooperating with the US in joint efforts to stamp out the estimated $50 billion drugs trade across the frontier. If Congress had its way, Mexico would have been added to the black list of countries like Colombia which are not cooperative enough and get no US aid.

What put the US on the spot and angered Congress was the recent arrest of Mexico's top antinarcotics policeman, Gen Jose Gutteriez Rebollo, accused of working for the main drugs cartel he was supposed to be rounding up. The US drugs czar, Gen Barry McCaffrey, had praised Guttierez's efforts just a few weeks before.

As US legislators and media denounced corruption in high places south of the Rio Grande, Mexicans fired back at American "hypocrisy" which ignored the fact that it was "consumer demand" in the US that was encouraging the drugs trade and that there was a flourishing guns traffic in the other direction.

Amid the war of words, President Clinton stood firm and refused to put Mexico on the drugs black list. He insisted on giving President Ernesto Zedillo and his government the benefit of the doubt. The stakes are too high to risk a major falling out between the two countries which share a 2,000 mile border along which there are about one million legal crossings a day and no one knows how many illegal ones.

President Clinton said on the eve of his visit that Mexicans "will in the end not be able to maintain the fabric of an orderly, democratic and free society if the narco traffickers come to dominate huge sections of their country".

The drug trade is, of course, also doing immense harm to the US, which can only tackle it with Mexican help. To help placate US critics, President Zedillo has just announced the abolition of the main anti drug agency and its replacement with a smaller and hopefully less corrupt body.

He told US journalists last week that the revelation that his anti drug czar was on the payroll of the drug barons was "the most difficult, saddest, bitterest moment of my administration". It was even worse than the collapse of the Mexican peso in the first weeks of his term in 1995, he admitted.

It was thanks to President Clinton that a $40 billion rescue package was put in place at that time to ward off Mexican bankruptcy and its world wide effects. Mexico has recently paid off the US part of the loan and the interest on it helped to reduce the US budget deficit.

It was President Clinton who fought doggedly early in his first term to secure approval for the NAFTA (North American Free Trade Agreement) binding the US, Canada and Mexico into a permanent trade pact. Critics, including many from his own Democratic party, accused the President of sacrificing US jobs for a pact with Mexico with little benefit for the US.

But in 1996, the third full year of NAFTA, trade between the US and Mexico reached a record $140 billion. Mexico's exports to the US in that year grew 17 per cent while US exports to Mexico increased by 25 per cent. Meanwhile, millions of jobs have been created in the US and unemployment is falling.

By the end of this year Mexico is expected to become the second largest trading partner of the US, passing out Japan and Canada. So closely are the two economies intermeshed that it is surprising President Clinton has not already visited Mexico after four years in office, but he is determined to pay more attention to Central and South America this term. After Mexico, he travels to Costa Rica for a Central American summit and then to Barbados for a Caribbean summit, at both of which he is expected to hold out the promise of eventual free trade agreements.

Later in the year, he will visit Brazil, Argentina and Venezuela. The US is anxious not to surrender trade and economic interest in its a own hemisphere to a growing EU involvement in the region.

Tougher US immigration laws are also causing resentment in Mexico, which risks having an estimated several million illegal emigrants sent back with all that entails in social disruption and loss of emigrant earnings to the poorer sections of the population. Again, Mexico sees an element of hypocrisy in the rhetoric and actions of the Republican controlled Congress.

Who would pick the tomatoes and grapes in California and do the menial jobs in the restaurants if there were not Mexicans to do it? When they were needed, these immigrants were welcomed but now they are to be deported after years of exploitation at the lowest wages, the Mexican authorities point out.

President Clinton, who signed the Immigration Bill, will also have to assuage offended Mexican feelings in this area.

How seriously he is taking the visit is shown by the 10 cabinet secretaries with him, including the Secretary of State, Madeleine Albright, and Attorney General Janet Reno. Joint working groups will assess bilateral relations in areas such as the environment, education, science, transport as well as drugs and migration.

The highlight of the visit will be when President Clinton "addresses the people of Mexico" in the National Auditorium on Wednesday. The President will also meet leaders of the main opposition parties. The US is mindful of the possibility that the ruling PRI party may lose control of the national parliament and the capital for the first time in almost 70 years in the July elections. That would show that Mexico is advancing towards a more democratic and open society but could also mean political unrest as the PRI tried to come to terms with such an upheaval.

President and Mrs Clinton spent a delayed honeymoon in Acapulco when he was a political nobody. That trip may have been more enjoyable than this one turns out to be.