FOR THE FIRST time since the military took over in 1973, Chile is witness to a national strike with heavy political overtones. Participation in the protest, and support for it by other social and professional groups, may be wider than it is deep. Nonetheless, Gen. Augusto Pinochet, the 10-year strongman, appears to have entered a new and difficult stage of his dictatorship. His position within the ruling elite is uncertain, while the unions, though hemmed in, and the political parties, though illegal, are getting bolder. It is becoming a question whether he can keep to his laughable plan to retain personal power for six more years, and only then and on his terms to let the politicians back in.

Aspects of Chile's situation recall the disintegration of the elected but erratic Marxist minority government of Salvador Allende. The economy is a disaster area: the Pinochet contribution is unemployment of 20 percent, inflation of 30 percent and a plunging national product. Many people and groups who were initially understanding, if not directly positive, feel the government is ruining and disgracing the country.

The force available to Gen. Pinochet, and his readiness to use it, cannot be underestimated. In different circles, nonetheless, the expectation is that sooner or later another group of officers may intervene to hasten the country's return to elections. The sooner they do it, the less costly the process and the less radical the result will be.

The Reagan administration set out in Latin America thinking that Chile was authoritarian but anti- communist and therefore fit for a warmer tie. Naval visits and official bank loans were resumed, Mrs. Pinochet was invited to tea at the White House, and so forth. More than two years later, however, Chile still has not met the minimal human rights tests needed to qualify for American aid. The administration policy has made the United States look more than a bit foolish for giving something of value and getting very little back.

In the current period, while he was turning a full presidential spotlight on abuses in communist-ruled Poland, President Reagan left it to the State Department to address the similar abuses in Chile. The State Department, meanwhile, waited to be asked to offer its views. These views, if and when finally uttered, are critical of Chile's arrests of union officials and supportive of a return to democracy; they have made quite a splash in Chile. The American ambassador, earlier criticized for the narrowness of his local contacts, conspicuously received a group of union leaders who were in effect eluding arrest.

It all makes us think of how easy, useful and satisfying it would be simply to have the American government speak in full voice of what the American people believe. Mr. Reagan speaks that way of Poland. Why not speak of Chile too?