Architect of Perestroika Steps Down : Politics: Alexander Yakovlev, Gorbachev’s senior adviser, gives no reason for his decision.

President Mikhail S. Gorbachev’s senior adviser, Alexander N. Yakovlev, the principal architect of perestroika reforms, announced his resignation Saturday after giving his support to a new liberal political movement that wants to accelerate and broaden the country’s reforms.

Coming virtually on the eve of Gorbachev’s summit meeting with President Bush here this week, Yakovlev’s resignation seems certain to embarrass the Soviet leader with its implication that another of his oldest and most trusted advisers finds the Soviet leader’s course weak and inconstant.

But Yakovlev, 67 and in poor health, has spent little time in his Kremlin office in recent months, and he had declared his desire to retire from public life at the Communist Party’s congress last summer.

“I am leaving the Mikhail Gorbachev team,” Yakovlev said in a brief statement Saturday. “I have submitted an application to the president to relieve me of my duties.”

Although Yakovlev gave no reason for his resignation, he had written in the newspaper Izvestia this month that “the revolution ‘from above’ has exhausted itself, doing all or nearly all it possibly could.”

And Saturday, Yakovlev broke with Gorbachev in expressing support for the recent order of Russian President Boris N. Yeltsin outlawing Communist Party cells in factories, offices and government institutions in the Russian Federation. Yeltsin’s decree has been criticized as unconstitutional and undemocratic by Communist leaders, including Gorbachev.

“It’s a normal approach,” Yakovlev said, referring to Yeltsin’s decree. “We are talking about a law-based state, and everybody should be treated the same.”

Yakovlev had joined other leading liberal politicians, including former Foreign Minister Eduard A. Shevardnadze, in founding the Democratic Reform Movement. He argued strongly for a multi-party political system to continue perestroika , as Gorbachev’s reforms are known, and to combat attempts by conservatives to reverse it.

“The shift toward catastrophe can be prevented only by creating and streamlining an efficient multi-party, parliamentary democracy in which the forces of leading parties could match one another,” he wrote in the Izvestia article. “This would result in a strategic victory--democracy as evidence of dynamic stability during this period of rather intensive and complex developments.”

Yakovlev, a historian who studied at Columbia University as an exchange student in the 1950s, declared that he has always favored “a sound and democratic bipartisan system” and urged the breakup of the Communist Party into its major political elements.

“The Communist Party is ‘pregnant’ with a multi-party system,” he wrote. “It would be only logical to realize that fact and think of a set of measures that could transform what we now have into a civilized multi-party system of a parliamentary type with minimized pain and for the good of society.”

But he gave a sharp answer Saturday when asked at a news conference for the new group whether Gorbachev could become the leader of the pro-democracy coalition. “No!” he replied, refusing to elaborate.

He also refused to say whether he is quitting the Communist Party, although reports circulated a few weeks ago that he would do so.

Yakovlev, an early champion of glasnost , or openness, in Soviet society and a defender of liberal thought within the Communist Party, has long been a hero of radicals within the party.

For the same reasons, however, he has been held in suspicion by conservatives and Russian nationalists even longer. In 1973, he was “exiled” to Canada as the Soviet ambassador for a decade because of his liberalism. Gorbachev arranged his return in 1983, and two years later, when he assumed power, he made Yakovlev his top adviser.

Liberal delegates at the party congress last year tried unsuccessfully to persuade Yakovlev to run for the top post of general secretary, still held by Gorbachev. He declined, saying he was stepping out of the party leadership, but he pledged then that he would never leave the party, which he joined as a soldier during World War II.

Yakovlev’s resignation will bring the final dispersal of the team that launched perestroika in April, 1985, to pull the Soviet Union out of the profound crisis that still grips it. Over the last year, many of Gorbachev’s closest associates have resigned or been replaced because of differences over the next steps in tackling the crisis.

On Saturday, Sergei Alexeyev, chairman of the independent Constitutional Compliance Committee, appealed to Yeltsin to suspend his decree banning Communist Party cells in workplaces, pending a review of its legality.

Alexeyev told a news conference that his committee will hold a public hearing into the legality of Yeltsin’s decree and issue a ruling within 15 days.

“If any act being drafted suppresses human rights, even to the smallest degree, it does not deserve further consideration,” Alexeyev said. “I’m not saying this does suppress human rights, only that it deals with human rights and will be the subject of our review.”

But the Russian Justice Ministry defended the decree as constitutional, saying it is intended to give equal rights to different public organizations in state affairs.

“The decree ensures the equality of rights of various public associations in the management of state affairs and expands the guarantees of the political rights of citizens,” the ministry said in a statement. “The decree . . . demands review and subsequent repeal of acts that create privileged conditions for the activity of one political party in comparison with others.”