Half a million infiltrators a year - this is the prevailing estimate. Half a million make their way almost openly across the porous border between Mexico and the United States and cross the desert to Los Angeles. Twelve million Mexican immigrants are living in America illegally. The irony is that the Promised Land to which they are coming will perhaps no longer be one if they continue to come. Their immigration brings with it an individual promise, but also the seeds of a collective calamity. The absorbing country - the slow, convoluted, bureaucratic giant - is not capable of dealing with the stunning flood.

More than 1 million immigrants demonstrated in the streets of the United States last week in support of proposed legislation that would help the illegals obtain legal status. "While we were watching them demonstrate," said one of the entertainers on nighttime television, "another million of them managed to slip in." The entire problem is encapsulated in this joke. In whatever direction the Americans look in their search for a solution, another problem is revealed. Perhaps they should simply accept the reality: The Mexicans will come, America will change. This is the way of the world.

The political battle over the future of the immigrants is raging on simultaneous fronts. The House of Representatives has, as is its wont, has passed a tough law that answers to the wishes of the public. More means for securing the border and defining aid to the immigrants as a punishable offense. The opponents of this law are many, and their reasons are varied.

The Senate, which has recessed for two weeks, but will have this as the main issue on its agenda when it returns, is trying to find a compromise that will satisfy everyone. Most of the formulas for legislation include increased control of the border along with increased quotas for legal immigrants and laundering of the illegals. The likely result is one of the two: either stagnation that will not allow legislation at all or legislation that is lukewarm to the point of uselessness. Too many forces are eliminating any possibility of formulating a unified and clear plan.

There are economists and businessmen who are warning of a blockage that will stop the flow of cheap labor from Mexico. Here is another joke from the nighttime television show: The good news is that we have succeeded in stopping the immigration. The bad news is that the price of a head of lettuce has gone up to $1,000. The coddled, consumerist United States needs the Mexicans as much as they need it. Just as it will find it difficult to reconcile its aims in the Middle East with the constant fear of a jump in oil prices, it will find it difficult to get accustomed to a reality in which there is no depressed labor force.

There are also humanitarian reasons for reservations about the tougher proposals. Will it be forbidden to give a glass of water to a thirsty infiltrator in the burning desert of Arizona because this is abetting illegal immigration? The number of those who die on the exhausting journey to America, in similar circumstances, began to rise from several dozen to several hundred a year at the beginning of the 1990s when then president Bill Clinton tried to improve the control of the border and forced the infiltrators into more distant and deadly routes. Although the opponents of immigration are warning against the porosity of the border, which is inviting to the thief and the terrorist, it is clear to everyone that the immigrants from Mexico are not coming to kill. They are coming to work, and to live.

The politics of immigration is also not as simple as it used to be. The public wants a solution, but has reservations about extreme measures and the huge demonstrations last week brought a new reality to the surface: the increasing electoral strength of the Latino immigrants. Although the illegals cannot vote, the number of legal Latinos is also increasing, and their birthrate is high. In large states like California. Florida Texas - and New York is rapidly approaching this - the whites have become a minority. The parties want the votes of immigrants from Mexico, El Salvador and Guatemala. There are legislators who do not want a solution and believe that the position they take will help them win in the elections in November.

In these circumstances, two scenarios are possible: The one is that the wave will continue, and in not very many decades America will be different. Already today there are areas where it is somewhat hard to recognize it. Perhaps this is the big, important story in the next American century. And there is no certainty that is would be bad for the United States: The immigrants will bring new energy and new ideas. The veterans will learn to get used to this (other countries, too, that are looking at the process from afar, also need to prepare themselves for the challenge. Here is a piece of advice for the Foreign Ministry: Increase the number of Spanish-speaking diplomats in North America).

The second scenario is one of an extreme event: for example, a terror attack that claims many victims and originates in Mexico, or a severe recession. An occurrence that would tip the seesaw of forces in a way that would enable the taking of extreme measures to block the immigration. In the absence of such an occurrence, it appears that the watershed has already been crossed. It is difficult to see at present a force strong enough to bring about the closing of the gates.