Amigos

In ideological terms President Reagan does not have much in common with President Lopez Portillo of Mexico. So it is doubly gratifying that Mr. Reagan is able to set philosophical differences aside in order to open a much-needed dialogue between the United States and its neighbor to the south. Mr. Lopez Portillo's visit to Washington ended with his saying, "I confess for the first time now, I have felt totally relaxed." That augurs well for future relations.

Rapport between leaders is not an automatic recipe for overcoming diplomatic problems. But it is certainly a vital ingredient in the White House failed to establish a close relationship with the Mexican President, and bilateral strains grew as a result. Mr. Reagan, by contrast, recognized from the outset the growing importance of Mexico in the hemisphere and the need to foster better ties.

He is absolutely right. Mexico, in the eyes of many Americans, may still be thought of as that colorful, sunny tourist haven down south. But today it must be seen as much, much more. Mexico is now the United State's third largest trading partner (after Canada and Japan). It is the United States's fourth largest supplier of oil. It is beginning to play a major role in the Caribbean region as well as in the global North-South discussions.

Not least of all, Mexico, because of its population explosion, impinges directly on the economic and social fabric of the US, letting immigration to the US serve as a safety valve while it gets its internal house in order.

In this situation it is crucial that the two nations develop a friendship that can weather their differences. Today's bilateral and regional problems were not resolved by the Lopez Portillo visit. But a good start has been made. Mexico has agreed in principle, for instance, to participate in the new US "mini- Marshall Plan" for the Caribbean Basin. Mr. Reagan, in turn, has accepted Mexico's invitation to attend the North-South conference of world leaders in Cancun in October -- a meaningful development in light of his skepticism about the whole process of dialogue with the third world.

There was progress, too, on the most sensitive issue -- Mexican immigration -- although this promises to touch off controversy and debate. Under a plan now in the making in Washington, the US would permit 50,000 Mexicans a year to enter the country to work legally. It would also grant amnesty to some 2.7 million Mexican "illegal aliens" thought to be in the US, allowing them either to receive temporary work status or to become permanent resident aliens. Would such a program stem the surge of illegal migrants over the border? Comment must await official announcement of the plan. But, in confronting the issue head-on, the US administration at least is moving in constructive directions.

One swallow does not make a summer and one presidential tete-a-tete in Washington does not lift the clouds over US-Mexican relations. But the people of Mexico and the United States should take note of a decidedly improved atmostphere.