Waiting for the results of last week's legislative elections, Charles de Gaulle could relax with the easy self-assurance of a national savior. All of the experts had promised him a majority every bit as handsome as the one he enjoys in the current Assembly.

By Sunday night, however, it was apparent that de Gaulle, and anyone who was reading the European or American press, had been sadly misinformed. The Association for the Fifth Republic -- the confederation of Gaullist parties that has had a firm grip on the Assembly for nearly ten years -- was in trouble. For a number of hours after the polls closed it seemed that the Association would not control even a bare majority. Only the following day when the Corsican vote was recounted, did the Gaullists gain their 244th seat, one more than the total held by all the opposition parties.

Despite the Association's loss of approximately 40 seats, one should not assume either that de Gaulle is in serious difficulty, or that a sizeable number of Gaullists have suddenly turned against the General.

Even if he had not won a majority of the seats, de Gaulle made it perfectly clear before the election that he would form a minority government if necessary. Prime Minister Pompideau, head of the Association for the Fifth Republic, and de Gaulle's man in parliament, should have no difficulty maintaining enough discipline in his party to keep the majority intact. He is a shrewd organizer, and the pressure of a narrow majority, should convince his followers to stay in line.

Pompideau also stands to benefit from the collapse of Senator Jean Lecanuet's Democratic Center party. This right-of-center group returned only half as many deputies last week as in 1962, the year of the last legislative elections. Gradually a number of Center Democrats will shift away from Lecanuet to join the Association for the Fifth Republic, making Pompideau's majority even more secure. In 1962 de Gaulle's original majority was only 12 but his party absorbed about 25 deserters over the next five years.

One can assume, therefore, that the new Cabinet will be exclusively Gaullist and that it will be cooperative and stable. The results of the election should have a negligible effect on the President's handling of the most important issues since no group in the Assembly is strong enough to challenge his leadership.

But de Gaulle has maintained more than just the political power of previous years. To a large extent his voting strength is undiminished. Even though he won many more seats in 1962, de Gaulle's popular vote was within a small fraction of the 37.5 per cent he received last week. Apparently there was no significant desertion by the President's former supporters. What changed was not the Gaullists but the opposition.

For the first time since the popular front of 1936 France's leftist parties formed a limited, tactical alliance to help them gain seats in the Assembly. The two major groups -- the Federation of the Left under Francois Mitterand (the man who nearly defeated de Gaulle in the presidential elections of 1965) and the Communists -- agreed to present a single candidate in as many districts as possible so that the leftist vote would not be split.

Under the intricate constitutional procedures of the Fifth Republic a legislative election consists of two rounds of voting. At the first balloting any candidate who received an absolute majority of the vote was declared the winner. In those districts where no candidate won a majority, a second round was held in which a plurality of the vote was sufficient for election.

For two days after the first round Mitterand met with Waldeck-Rochet, the leader of the Communists, to decide which leftist candidates should step down. When the two groups originally planned the alliance they assumed that the leftist candidate with the most votes would continue into the final-round and all others would withdraw. In many districts, however, a Communist polled more votes than a moderate socialist yet still had no chance of winning even if the other leftists withdrew. The leaders of the left assumed that while most Communists would vote in the second round for a socialist, there were thousands, perhaps millions, of socialists who would vote for a Gaullist before they would vote for a Communist.

Waldeck-Rochet and Mitterand reached a remarkable agreement during their negotiations after the first round. They decided that the strongest place candidate should proceed into the final round even if he had not received more votes than the other leftists in the first round. With unprecedented cooperative spirit the Communists agreed to sacrifice 15 of their own candidates who had polled in the first round more votes than the socialists they eventually supported.

Equally extraordinary was the discipline of the Federation of the Left. Only three socialists refused to step down in favor of a Communist. Dozens of others, many of whom had waged bitter anti-Communist campaigns, followed their party's command and urged their supporters to vote Communist.

Ironically, it was precisely this leftist solidarity that had encouraged de Gaulle's optimism. He assumed that a unified left in which the Communists appeared to be the senior partner would so terrify the average French voter that he would cling defensively to the Association for the Fifth Republic. What very few observers anticipated was that the rank-and-file of the leftist parties might have the same discipline that their leaders had recently acquired. By pooling the votes of the Federation of the Left and the Communists, the new popular front snatched many supposedly safe Gaullist seats.

The leftist alliance was no more than an electrol arrangement designed to defeat Gaullists wherever possible -- there was no attempt to formulate a joint postelection program. But the experiment will have important implications for the future. It demonstrates that Waldeck-Rochet's efforts to lead the Communists out of their ghetto have largely been successful. An alliance with a Communist is no longer, apparently, the kiss of death in French politics.

The cooperation suggests, furthermore, that when de Gaulle steps down from the Presidency some time in the next few years, a leftist will stand an extraordinarily good chance of succeeding him. The candidate of the united left, certainly not a Communist, would likely be Mitterand or Guy Mollet -- a disliked but very skillful former leader of the fourth Republic. Another Fourth Republic figure, Pierre Menders-France who made his political comeback in Grenoble last week after unsuccessful attempts in 1958 and 1962, is one of the most intelligent and reform-conscious of all Socialist leaders. Mendes has a very large following, but he is so opposed to the presidential system in principle that it would be difficult to convince him to seek the office.

Whoever the united left puts forward to oppose de Gaulle's choice for a successor, there is an excellent chance that he can win if the parties do not forget the lessons of this week's election. A flexible, and cooperative posture has provided them with their best electoral showing in a decade. The left has proved that even with the President still in office his regime is vulnerable. Once de Gaulle steps down it may be impossible for him or anyone else to keep the leftists out of power.