MOSCOW, JULY 14 -- The Soviet Communist Party symbolically surrendered its domination of all state institutions today by excluding senior government figures from its ruling Politburo for the first time since the 1917 Bolshevik Revolution.

Traditionally regarded as the seat of real power in the Soviet Union, the Politburo now seems likely to give up much of its authority to the new presidential institutions established by Mikhail Gorbachev.

Soviet officials said the newly expanded 24-member Politburo chosen today by the party's newly elected Central Committee would confine itself to broad policy goals and internal party matters rather than interfere in the day-to-day running of the country. Shifting the base of power in the Soviet Union from the Communist Party to the government has been a goal of President Gorbachev's reforms for the past two years.

Gorbachev, who was reelected as Communist Party general secretary at the 28th party congress that ended Friday, is one of only two holdovers from the old Politburo to be appointed to the new body. The other is the newly elected deputy general secretary, Vladimir Ivashko, the former party leader in the Ukraine.

Senior officials dropped from the Politburo include Prime Minister Nikolai Ryzhkov, Foreign Minister Eduard Shevardnadze, KGB chief Vladimir Kryuchkov, state planning chief Yuri Maslyukov and Defense Minister Dmitri Yazov. All have been appointed to the newly formed Presidential Council, which serves as an advisory body to Gorbachev, and all remain in charge of their ministries or government functions.

"This serves to underline that the party is totally breaking with the former practice when it was incorporated into the command-and-administer system and was at the top of the hierarchy," said Ivan Frolov, editor of the party newspaper Pravda and a member of the new Politburo.

"The party will be competing with other social and political forces and seeking to establish its predominance mainly through an ideological and political struggle," he added.

Gorbachev has sought to reshape the party to help it reach out to "other democratic forces" that are breaking away from the party and to withstand the challenge from unhappy workers and consumers.

The new Politburo is dominated by the Communist Party leaders from each of the Soviet Union's 15 republics. But it also includes senior party secretaries proposed by Gorbachev, many of whom are in their early fifties, and Moscow party chief Yuri Prokofiev, a moderate reformer close to Gorbachev.

The Politburo began losing its importance over the past few months since Gorbachev was elected to the new post of executive president. Decisions that used to be referred to the Politburo as a matter of routine -- such as whether to deploy military units in an emergency -- are now made by the president or the government.

Frolov told reporters today that the Politburo, which traditionally met every Thursday, would hold monthly sessions. The logistical difficulties of summoning Politburo members to Moscow from across the country is likely to further reduce the significance of the body.

In addition to the government ministers who have been dropped from the Politburo, several senior party officials have gone into retirement. They include former agricultural chief Yegor Ligachev, ideology chief Vadim Medvedev, economics expert Nikolai Slyunkov, former Russian president Vitaly Vorotnikov and defense industry chief Lev Zaikov.

Ligachev, the leading conservative and challenger to Gorbachev on the former Politburo, has been replaced as party secretary responsible for agriculture by Igor Stroyev, his effective understudy for the past year. Stroyev, a Gorbachev appointee, is regarded as somewhat more ready than Ligachev to encourage family farming as an alternative to state farms.

The new ideology chief will be Alexander Dzasokhov, a former Soviet ambassador to Syria and chairman of the international affairs commission of the Supreme Soviet legislature. Gennady Yanayev, the head of the official trade union movement, will be responsible for international affairs in the Politburo.

The Central Committee also elected a 16-person Secretariat, five of whose members are on the Politburo. The Secretariat, which will meet once a week under the chairmanship of Deputy General Secretary Ivashko, will supervise the day-to-day running of the party.