Gaullist leader Jacques Chirac and President Valery Giseard d'Estaing are trying to reach a political truce after seven months of open conflict that pushed the ruling centrist-Gaullist coalition to the brink of dissolution according to informed political sources.

The still-tentative truce awards Chirac the politically dominant role within the coalition between now and the National Assembly elections scheduled for March 1973, according to these sources.

Prime Minister Raymond Barre, whom Giscard had been trying to build up as the coalition's political leader, would reportedly devote himself almost exclusively to economic policy if the truce is firmly agreed on at a luncheon Friday between Barre and Chirac.

Chirac's re-emergence as top political strategist within the coalition would give a much sharper anti-Communist tone to the March elections. He favors direct confrontation with the united front the Socialist and Communist parties have formed fro the election.

Today the conservative dailt L'Aurore published a poll showing that the Deflist alliance would win an overall majority of elections held now, and the government announced that it will move to tighten the rules covering such polls.

The 56 per cent the opposition alliance received in the poll was the highest total so far credited to the left in a poll.

Chirac publicly broke with Giscard and quit as prime minister in August, in part because Giscard did not favor confrontation politics. He directly challenged Giscard's small Independent Republican Party and humilated it by reorganizing the Gaullists and winning the race for mayor of Paris in March.

The president has been pushing Barre as a political counterweight to Chirac and to the left. The portly economics professor, who stresses that he is a technocrat and not a party politician, quickly won high positive ratings in public-opinion polls.

But Barre's increasingly shrill denunciations of labor unions and his open involvement in political party maneuvering on Giscard's behalf has begun to depress those ratings, and his prestige suffered enormously last Thursday when he angrily demanded that the Gaullists support his economic program or accept the responsibility for voting him out of office.

The Gaullist deputies stunned Barre by going into a caucus and making it clear that they were prepared to abstain and let the left vote his government down. Chirac intervened at the last moment and, according to the Gaullist version, saved Barre's government by getting the Gaullists to support him.

Political analysts do not discount the possibility that a good deal of the Gaullist revolt was stage managed. Even if so, Barre emerged from the conflict in Parliament badly isolated, scarred and finally convinced that the Gaullists would push the quarrel to the point of topping his government.

The impending rapproachement, now-ever guarded and wary, has already helped bring the departure of publisher Jean-Jacques Servan-Schreiber, an implacable foe of Chirac, from Giscard's immediate political entourage. Servan-Schreiber announced last week that he was resigning the special administrative reform study mission Giscard ostentatiously awarded him in March, and he abstained in the National Assembly vote of confidence rather than vote for Barre.

Another significant sign of a more conciliatory atmosphere within the coalition has from Jean-Pierre Soisson, appointed last week as secretary general of the Independent-Republicans.

Soisson effectively takes over operational control of the party from Michel Poniatowski, another bitter Chirac foe. Pontiatowski, who was dropped as interior minister last month when Barre reshuffled his Cabinet, has reportedly turned down Giscard's offer to send him as ambassador to Bonn.

"The war of words is over," Soissons said at a press conference Wednesday morning. He pledged to work for "a new image" and "a new climate" within the coalition, "which will have an electoral program to fight and win the elections."