The race to succeed Boris Yeltsin as the president of Russia took an important turn today as two of the most powerful and popular contenders announced that they are joining forces, creating a centrist alliance independent of Yeltsin.

Yevgeny Primakov--a former prime minister, foreign minister and redoubtable survivor of Kremlin intrigues for more than a decade--emerged from months in the shadows to announce that he will chair a fast-growing electoral bloc founded by Moscow's ambitious mayor, Yuri Luzhkov.

Their immediate goal is to capture seats in the lower house of parliament, the State Duma, in the Dec. 19 election. But both are also leading candidates for president in next summer's vote. Primakov acknowledged that they have not yet decided which one will be the presidential contender from the new bloc, Fatherland-All Russia.

"We will come to terms," Primakov told a crowded news conference in response to a question about who will run for president. Primakov remains among the most popular of all Russian political figures, and Luzhkov is extremely popular in Moscow. In recent nationwide surveys by the Fund for Public Opinion, Primakov was chosen by 19 percent of respondents who were asked whom they would choose as president if the election were held today. Luzhkov was third in the poll with 9 percent, following Communist Party leader Gennady Zyuganov, who was chosen by 15 percent of those answering the survey.

With Luzhkov among the politicians at his side, Primakov announced that he will head the party's list of candidates for parliament, with Luzhkov second. A strong showing in the parliamentary balloting could be a valuable springboard for either of them in the presidential contest next spring.

Luzhkov's movement, which has been gaining strength in recent months, includes politicians with drastically different outlooks--for example, on the issue of land reform, which has been stalled for years. But a central thread is that many represent what is called here "state capitalism." They are former Soviet officials who have come to accept that Russia should be a market economy, but who also want the state to control and regulate the market, and to choose winners and losers.

The alliance also includes a grab bag of views about Russia's place in the world and its relations with the West. Luzhkov has periodically offered strong nationalist views. Primakov, too, has been distrusted by many in the West because of his long-standing links to Iraqi President Saddam Hussein. But in his comments today, Primakov called for "the rejection of both nationalism and chauvinism."

Luzhkov also is on the December ballot for reelection as Moscow mayor. It is possible that neither Luzhkov nor Primakov actually would take up seats in the Duma if they won them, but would instead relinquish their chairs to others down the party list.

Half of the 450-seat Duma is elected based on votes for party lists and half on votes for specific candidates in local districts.

The Kremlin is anxiously watching Primakov and Luzhkov. In recent years, Yeltsin has tried with limited success to create centrist political blocs that would fall under his wing. Yeltsin, deeply unpopular at home, seems to have lost some influence over the coming election campaign, and the Kremlin inner circle has been fuming about the formation of Luzhkov's bloc. Boris Berezovsky, the outspoken tycoon who is part of Yeltsin's group, recently declared that neither Luzhkov nor Primakov should become Yeltsin's successor.

Luzhkov accused the Kremlin of trying to thwart the alliance. "We were aware of powerful pressure and opposition to formation of our bloc," he said. "But we are not afraid of it. We are strong."

The new alliance includes a group of regional bosses, among them St. Petersburg Mayor Vladimir Yakovlev and Tatarstan President Mintimer Shaimiev. Today the head of the Agrarian Party, Mikhail Lapshin, previously an ally of the Communists, also joined.

The Luzhkov group has gained support in part because of the weakness of other parties and partly because Yeltsin has not groomed a politically viable successor. Yeltsin's recent announcement that his new prime minister, Vladimir Putin, would fill that role has been met with skepticism and derision by political analysts. Sergei Stepashin, the prime minister Yeltsin fired last week, said today he would run for parliament from a district in his native St. Petersburg.

Primakov, who will turn 70 this fall, was ousted as prime minister by Yeltsin last spring, then slipped from view for several months when he underwent back surgery. Some analysts speculate he might run for president while promising to make Luzhkov his premier or vice president. Primakov announced today he would favor rewriting the Russian constitution to create the post of vice president, which currently does not exist.

CAPTION: Yevgeny Primakov, left, and Moscow Mayor Yuri Luzhkov, two of the most popular politicians in Russia, announce formation of their centrist bloc.