Argentina's military junta began meeting tonight to choose a new president amid strong indications that the traditionally predominant Army leaders would move to force the selection of another general to replace the ousted Leopoldo Galtieri.

The three-member junta met for two hours tonight in the Army headquarters building, then issued a statement saying its deliberations would continue Sunday. Sources close to the armed forces said that the military leadership continued to be stricken by feuding and maneuvering between the politicized commands of the three service branches, while Argentina's government remained nearly paralyzed.

Gen. Alfredo Saint Jean, the interior minister who last night was assigned temporary presidential powers by the junta, stayed at the presidential palace today only long enough to meet with the irrigation minister of Iraq, officials said, before leaving for another stormy round of political meetings with other Army generals.

The choice of a new president dealt less with policy and ideology than personalities and the power prerogatives of the Army, Air Force and Navy, according to informed political sources.

Air Force Commander Basilio Lami Dozo was reported to be seeking the top government post on the strength of the Air Force's record in the Falklands conflict. He was being opposed by the leaders of the traditionally dominant Army, who, led by new Commander-in-chief Cristino Nicolaides, were expected to insist that an Army general be named president.

Army commanders met this morning to discuss their candidates for the job, and reports tonight said Nicolaides had emerged as a leading candidate, promoted by the Army in the junta negotiations.

Nicolaides, who yesterday was sworn to replace Galtieri as Army commander, is considered one of the most conservative leaders of the armed forces because of his vehement anticommunism and distaste for the traditional democratic leaders. Political leaders have warned privately that Nicolaides' installation in the powerful executive position of president as well as Army chief could lead to sharp conflicts with party politicians.

Other possible presidential candidates reported to be under consideration by Army leaders were Gen. Juan Carlos Tremarco, a corps commander and leading opponent of Galtieri, and retired generals Antonio Domingo Bussi and Jose Rogelio Villarreal.

While the decision on the president was expected to be made as early as Sunday, sources stressed that the political upheaval within the armed forces caused by Argentina's failure to retain the Falkland Islands could continue for some time.

Army leaders were said by sources close to the military command to be intent on forcing the resignation of both Lami Dozo and the Navy commander, Rear Adm. Jorge Anaya, the two other junta members who shared responsibility with Galtieri for the Falklands invasion and the subsequent failure to negotiate a settlement with Britain.

Meanwhile, the armed forces leaders were still far from reaching a consensus on the policies the new government should adopt or how it would proceed in pressing Argentina's claim of sovereignty over the Falklands.

"First, the services have to stop fighting over the presidency," one political source explained. "Then they will have to resolve who is in the junta and what the government will be before they can start working on programs."

As is traditional in Argentina's repeated military power struggles since 1930, this week's political turmoil has taken place in the heavily guarded headquarters buildings of the three services.

Civilian political leaders have met furtively with the leading contenders for president, but have made no attempt to intervene in the crisis. The streets have remained quiet, and most citizens have seemed absorbed in daily activities or Argentina's competition in the World Cup soccer championships while waiting for the military to act.

The only visible signs of a governmental crisis since a violent antigovernment demonstration on Tuesday have been the public ceremonies in which Galtieri was removed from his posts as president and Army chief and his replacements installed.

Newspapers have followed the power struggles minutely but from a distance, while serving as forums for statements, proposals and threats from the three services.

Today's papers carried declarations by unidentified Army leaders that Anaya and Lami Dozo should be obliged to resign, along with hints from the Air Force that it would reverse Argentina's economic policies and return the country quickly to democracy if Lami Dozo were president. Navy leaders were presented as neutral in the presidential struggle but determined to keep Anaya as their commander.

Traditionally here, the actual military power of various armed forces leaders--that is, the ability to mobilize troops and armor--is a determining factor in settling disagreements. But in most cases, such action is in fact avoided. Instead, military leaders plunge into an elaborate series of alliances and backstage maneuvering, sometimes collecting the support of military units like pieces on a chess board without ever mobilizing them.

Because of its vastly superior forces, the Army rarely loses a political battle among the services once its leaders are united, and Argentina has never had a military president from the Navy or Air Force. In addition, Army leaders have in the past been able to force the reorganization of the other two services.

For this reason, most political observers today expected the Army to win out in the meeting of the three-member junta, halting the candidacy of Lami Dozo and imposing the selection of one of a list of generals that would be submitted by the Army for the junta's consideration.

But political sources noted that the Army had been badly weakened by its failure on the Falklands, in which Army troops did not offer the strong resistance to British forces that for months was promised to the Argentine public.

In contrast, the Air Force pilots who attacked and sunk five British ships have emerged as the heroes, and Air Force commanders have been quick in attempting to exploit that advantage politically.

Lami Dozo has made frequent public appearances and offered ample statements to reporters hinting that he backed government-directed economic development and a transitional military government--policies favored by civilian political leaders.

The Air Force commander has also met with leaders of major political parties in recent days in an apparent effort to consolidate popular support that could be used to pressure military leaders. Political observers said today that Lami Dozo's position remained formidable and that it was possible that the combination of Navy and Air Force leaders could overrule the Army during the struggle over the presidency.

Reports today also said Lami Dozo could attempt to propose Air Force Brig. Gen. Jose Miret, the current government secretary of planning, as president in place of himself, or even a civilian as a compromise.

Meanwhile, leading political parties said they were working on proposed plans for a transition to democratic government that they expected to announce in the next few days. Political sources said party leaders still had strong hopes the new military government would negotiate directly with civilian leaders and allow them broad influence while elections were planned for 1983 or 1984