TAIPEI, TAIWAN -- Liberals in Taiwan's ruling Nationalist Party appear to have won the first major political struggle following the death of president Chiang Ching-kuo as momentum builds to name his successor, Lee Teng-hui, acting chairman of the party.

The chairmanship of the party, known as Kuomintang (KMT), is believed to be a key post for consolidating power. The party chairmanship is likely to strengthen Lee's ability to carry out the domestic political and economic liberalization begun by Chiang, according to moderates within the party.

For Lee, who has no power base and few ties to the party, military or security establishment, the appointment would be a logical political choice, in the view of some analysts, because it would give the appearance of party unity while reducing speculation about his presidential authority.

"If Lee were to become the head of the country and not the party," said a prominent newspaper columnist, "people would suspect that he is just a figurehead and a situation like this would not be good for either the government or the KMT."

There is strong opposition to Lee, however, from conservative party members from the mainland who view Lee, a native Taiwanese, as a threat to their domination of political power. But most local newspapers are predicting that if party leaders can reach an agreement, Lee could be appointed acting chairman as early as Wednesday, when the Central Standing Committee is scheduled to hold its regular weekly meeting, or at the first meeting following Chiang's funeral later this week.

Approximately 85 percent of the island's population is native-born Taiwanese, but Taiwan's politics have been dominated by an aging group of Chinese who fled to the island from the mainland after their defeat by the Communists in 1949.

Some analysts in the United States also believe that an oral message of support sent last Monday from President Reagan to Lee may have strengthened his hand within the party.

The first sign of a struggle appeared Jan. 17, four days after Chiang's death. Local newspapers carried a United Press International story that quoted "well-placed party sources" as saying Lee would be named to fill the vacancy left by Chiang. According to the report, a private poll was taken and an "overwhelming" majority of the Central Standing Committee's 31 members were in favor of Lee.

Party officials immediately denied that a poll had taken place. But the consensus among many political observers here was that the story may have been leaked by sources within the party as a way of promoting Lee or as a trial balloon to gauge public support for his appointment as chairman.

Party officials were caught by surprise the following day when Taiwan-elected ruling party legislator Chao Shao-kang brought the debate into the open when he presented the party headquarters with a proposal signed by 39 other locally elected legislators calling for Lee to be made acting party chairman until the 13th party congress convenes July 7.

About two-thirds of the more than 300 members of the Legislative Yuan, the formal lawmaking body, are ruling party members in their seventies and eighties, elected on the mainland in 1948. No national elections have been held since then on the grounds that free elections cannot be held on the mainland for these seats and elections in Taiwan would undermine the island's claim to authority over all of China.

The pressure to name Lee increased when the progovernment China Times carried an editorial last Tuesday calling on the party to make the appointment. Sources inside the paper attributed the editiorial to Yu Chi-chung, chairman of the newspaper and a member of the party's Central Standing Committee.

Party officials hurriedly called off the next day's weekly meeting of the Central Standing Committee, and the party's secretariat and its department of cultural affairs gave conflicting explanations to the press for the cancellation.

By week's end, the party came under even greater pressure as members in the National Assemby and the Control Yuan, the nation's highest watchdog body, put together similar proposals.

Liberals strongly backed Lee because they felt the Cornell-trained economist was progressive and would be the best person to continue Chiang's reform program.

Candidates backed by conservatives include Premier Yu Kuo-hwa, who party officials say has public-image problems, and party leaders feared that if he were made party chairman, it would damage the party's image as well. Hwang Shao-ku, 86, a conservative presidential adviser and another leading candidate, was ruled out because of his age and opposition from liberals. Despite reports that some members of the old guard were supporting Madame Chiang Kai-shek, the late generalissimo's widow, few took her candidacy seriously.

A state funeral is planned for Jan. 30, but few major world leaders are expected to attend since the island has diplomatic relations with only 23 countries. President Lee Kuan Yew of Singapore, a close friend of Chiang's, is to attend even though Singapore does not have diplomatic ties with either Beijing or Taipei.

President Reagan has asked William French Smith, a personal friend and former U.S attorney general, to head the unofficial U.S. delegation to Taipei.