TAIPEI, Taiwan (AP) _ President Lee Teng-hu was unanimously endorsed Sunday by the governing Nationalist Party as its presidential candidate, virtually assuring him of a six-year-term.

Lee's choice of a top personal aide as vice presidential nominee also received the backing of the party, although it angered many elderly conservatives who would have preferred the post go to Chiang Wego, son of the late Nationalist leader Chiang Kai-shek.

The 74-year-old Chiang Wego, an army general, is secretary-general of the National Security Council.

All 180 members of the Nationalist Party's Central Committee stood up to approve Lee, the 66-year-old former vice president who succeeded President Chiang Ching-kuo when he died in office in January 1988.

His tenure as president has been marked by policies designed to strike a balance between the conservative Old Guard of the party and an increasingly restless population clamoring for more freedom.

The National Assembly, or electoral college, is expected to approve Lee's nomination at a meeting March 20.

The committee later unanimously supported Lee's candidate for vice president, Li Yuan-zu, a former justice minister who is now secretary-general to the president.

Although Lee was assured of the nomination, there was intense speculation over whom he would propose for vice president. Aging conservatives and younger reformers who have differed widely over the pace of democratic change lobbied hard to influence the decision.

Lee, 66, the first native Taiwanese to head the party and government, appeared to be staking out his independence with the nomination of Li.

In a speech to the convention, Lee tried to reassure both the Old Guard and reformers that he had their interests at heart.

He urged convention delegates to unite and continue the democratization process initiated by Chiang Ching-kuo, who in 1987 lifted martial law that was first imposed by his father, Chiang Kai-shek, 38 years earlier.

''We are facing rising demands from the public and keen competition from the opposition party,'' Lee said. ''We need to review related constitutional problems so we can create more room for further progress.''

The Nationalist Party lost several key local seats in Taiwan's first multiparty general elections in December as the public vented displeasure at the slow pace of reforms to dismantle a political system that perpetuates Nationalist rule.

Lee also reasserted the party's commitment to seek reunification with China, a demand of the old guard politicians who fled to Taiwan with Chiang Kai-shek in 1949 after losing a civil war to Communist forces on the Chinese mainland.

''A new opportunity is created for our reunification with China as Communist regimes in the world are facing the destiny of outright collapse if they do not introduce drastic changes,'' Lee said.

''Our utmost task is to unite all anti-Communist forces to topple the Chinese Communist tyranny,'' he added.

Li, the vice presidential nominee, is from the Chinese mainland but that does not appear to have enthused the aging mainland-born conservatives who dominate the National Assembly.

Although the aging Nationalists are uncomfortable with Lee, many fear a popular uprising against the party if he is not elected. Opinion polls have found his public approval rating to be more than 80 percent.

The aging assembly members, who occupy 658 seats, were elected before 1949 and were frozen in office to support the Nationalist claim to be the sole legitimate rulers of all China. The remaining assemblymen are Taiwan-elected members and Nationalist-appointed members representing overseas Chinese.

Lee has encouraged retirement among the elderly in the National Assembly and the Legislative Yuan, Taiwan's legislature which also is dominated by aging conservatives. So far, few have accepted the handsome pensions offered for voluntary retirement.