Behind the crazy past and unpredictable future of the presidential race this year there lies a stunning reversal of regional roles. The basic building blocks of American politics are in flux.

The South has lost the moral authority that won for Jimmy Carter in 1976.

The Northeast, in decline but no longer on the defensive, offers prospects for a third party. The Southwest and West combine enough power and confidence to make possible a victory for Ronald Reagan.

The economic decline of the Northeast is an old story. Since World War II the country as a whole has shifted more and more toward services and away from the heavy industrial base that dominated the area ranging from New York through New Jersey, Pennsylvania, Ohio, Indiana and Illinois.

For most of this period, the Northeast has been self-deprecatory. It deplored the harshness of its industrial regime in the 1940s and 1950s. It apologized for its race prejudice in the 1960s. During the past decade, it suffered paroxysms of guilt because of the foreign policy excesses of the "Eastern Establishment."

The new element is a self-assertive attitude toward the rest of the country.

First New York City and now Detroit, with the Chrysler loan, put the arm on Washington for money. Sen. Kennedy, the favorite Democrat of the area, spoke of a Marshall Plan to "reindustrialize" the northern cities. Governors from New York through Illinois are rallying to a proposal -- enunciated by Felix Rohatyn of the investment firm of Lazard Freres -- for a government finance company to revitalize the inner cities of the area.

John Anderson has touched the same chord with a call for tilting tax revenues from the energy-rich states to the Northeast. Running on that platform, and with adequate funds and good, organization, he has a shot at carrying Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Michigan and maybe even Illinois.

The Old South has absorbed some of the waning economic power of the Northeast. Atlanta Memphis and New Orleans have had their boom times. The burden of black poverty has been lightened by migration from the farms to the northern cities.

But the true secret of southern success is moral and cultural. Faulkner and two, generations of lesser writers set against the collapse of industrial life in the North the superior humanity associated with communion in the more settled, rural life rooted amidst kith and kin. Southern generals and senators showed the way to victory in World War II, and the Cold War that followed.

Beginning in the 1960s, a new crop of educated southern whites vaunted the "soul" of Dixie as exemplified by success in coping with the obsession of race. Southern humanity was extolled as a cure for all the country's economic and foreign policies. It was billed as a way to give the United States a government "as good as its people."

The combination of southern moralism and northern guilt yielded the victory of Jimmy Carter in 1976. But compassion has failed to solve either national or international problems. The flop of the Carter administration has sent even southerners in a quest for roots.

It is revealing that Hodding Carter III, the most successful spokesman for the foreign policy of the Carter administration, is leaving the State Department to write a biography of his father -- the great anti-segregationist editor from Greenville, Miss. Equally that Willie Morris is now turning back from years as a successful literary figure in New York and Long Island to teach in Oxford, Miss., the heart of Faulkner country.

One section of the country has experienced neither loss of power nor decline of faith. The great stretch sweeping northwest from Texas through the Rocky Mountains and the West Coast to Alaska continues to drive forward.

Many of the rsidents are recent immigrants, living -- unlike the inhabitants of, say, Cleveland -- where they want to live. When things go wrong, they don't hesitate to go back to the drawing boards and start anew. They comprise the front end of the country. They are rich in the capacity for innovation in politics, culture and what is called life style. In Ronald Reagan, they have found a candidate who expresses their easy confidence and laid-back attitude.

It is difficult, in these conditions, to see the future clearly. Carter may again put together enough of the old South and the old North to eke out a victory. But Reagan could easily win, and Anderson certainly has a chance.

What is clear is the shift toward a new distribution of regional power. The adjustment will cause strain, and may take years. But until it is completed, the United States can probably not enjoy the blessing of strong leadership.