Chile and its military dictator, Gen. Augusto Pinochet, reach a crossroads Sept. 11 when the nation's 11 million people are scheduled to vote on a new, military-drafted constitution that would allow the government to remain in power until 1997.

Rising opposition to Pinochet and the coming plebiscite, however, have raised doubts about the vilidity of the vote and, increasingly, the ligitimacy of the regime itself.

Ten years have passed since Chileans last voted for their president, and the proposed constitution and plebiscite have served more to rally opposition than to solidify support for military rule. Recent calls for abstention or a "no" vote on the ballot have come from leading opponents within Chile and some observers feel that the end of the current government may be approaching.

Sources at the Organization of American States in Washington say they have been actively polling members to see if there is enough support for a resolution condemming the vote for lack of guarantees. No decision has been made. The OAS conceivably could call for postponement of the vote, although it is not clear whether key states within the organization, such as Mexico and newly democratic but still cautious Peru, would support such a move.

In a country that has not had free and fair elections since Pinochet overthrew socialist president Salvador Allende Gossens in 1973, many fear that ballot boxes will be stuffed and the results falsified, bringing about what Christian Democratic leader Patricio Aylwyn has called "the consolidation of the dictatorship."

One OAS diplomat concerned about the vote said that it is "80 percent probable" that Pinochet will "win" the plebiscite. Yet, "there is a very small chance, but still a chance that Pinochet will fall" as a result of increasing opposition to his one-man rule that has surfaced since the announcement of the plebiscite and the wave of right-wing violence that preceded it.

Chile is one of several countries in South America that wants to cultivate an international image of making an attempt to return to democratic rule, although few in the country believe Pinochet is democratically oriented or even seriously interested in widespread popular participation. His goal of "authoritarian democracy" was clarified when the text of the proposed constitution was released last month.

Since the 1973 coup, Chile's military has justified its intervention in the political process by pointing to the "excesses" of the pluralist democracy that existed under the 1925 constitution, and that had led to mass political participation by all groups in Chile.

Chilean political groups -- such as the centrist Christian Democrats of former president Eduardo Frei -- that supported the violent military intervention ending Allende's "experiment" in socialism" now fear they will never again participate or enjoy democratic liberties once taken for granted under the Chilean political system.

Under the proposed constitution to be voted on next week, Pinochet would be allowed to rule for up to 16 more years, until 1997, and congressional elections would come in 1989 at the earliest. In the meantime, the military and its civilian supporters would continue economic and structural changes they began instituting in the mid-1970s, consolidating their hold on the nation.

Opposition to Pinochet's rule has been growing in Chile in recent months, and some political experts see his decision to call a plebiscite as a major tactical blunder in his effort to remain in power. Diplomats there believe that sectors within the military itself see the need to replace the 65-year-old general with someone more "presentable" both inside Chile and to the international community.

A sign of the military's opposition to Pinochet -- centered primarily among the Air Force and dissident sectors of the Navy -- came last week when retired Gen. Gustavo Leigh publicly stated his opposition to the plebiscite because the draft constitution represents the "institutionalization of a personalist, absolutist dictatorship."

Leigh was an original member of the four-man junta that seized power in 1973, but was removed by Pinochet when he began publicly challenging the dictator. His removal brought about the resignation of 18 of the Air Force's top 20 officers. Many top Air Force personnel, say well-connected officials in Santiago, remain loyal to Leigh.

Civilian opponents have also been outspoken in criticizing the plebiscite. Frei, former president and still the major figure in the Christian Democratic Party, has called for a two-year transition government, and a constituent assembly. Some view this as an invitation for younger, more moderate officers to intervene.

Frei, 69, was Chile's president from 1964 to 1970, and initially supported the military intervention. He and fellow Christian Democrats blocked many of Allende's Popular Unity programs in the Congress from 1970 to 1973, and are still heavily criticized in Chile by those who believe they helped precipitate Allende's overthrow.

Ironically, the Christian Democrats have in recent weeks talked of a possible coalition with the left, once considered its major enemy. This in itself is a measure of the extent of opposition to the current regime.

"The people will vote, but I am certain that the official vote count will not reflect the true vote," Frei said recently. Unlike elections under earlier regimes, no electoral roll exists and those counting the votes will be handipicked representatives of the military, including mayors chosen by Pinochet.