The Betting in Washington Is on Yeltsin : Policy: The grudging conclusion taking shape is that Gorbachev will lose out in the power struggle.

Officials in the Bush Administration are moving toward a reluctant consensus that Soviet President Mikhail S. Gorbachev will lose the struggle for power in the crumbling Soviet Union and that the United States must now focus its diplomatic attention on Russian Federation President Boris N. Yeltsin.

As President Bush met Wednesday with his top national security advisers, his ambassador to Moscow told Congress that Yeltsin will “unquestionably” become the dominant American partner. Still determined to maintain a hands-off public stance, rather than undercutting Gorbachev, Bush insisted that, as the Soviet Union continues to fly apart, the United States can only “let that evolve.”

But well-placed Administration officials said privately that Yeltsin has now clearly gained the upper hand in his bid to form a new commonwealth and that Gorbachev--still the emotional favorite of top U.S. policy-makers--may be relegated to a powerless state.

U.S. Ambassador Robert S. Strauss, who had voiced strong doubts a day earlier about whether Yeltsin could succeed over Gorbachev’s opposition, said Wednesday after consulting with aides in Moscow that he now believes the Russian president will triumph.

“That will put Yeltsin in a very strong position” in relation to Gorbachev, whose influence “is on the decline,” Strauss told the House Armed Services Committee. “Unquestionably, President Yeltsin and his various ministers are the ones with whom we will deal.”

The indications of the U.S. position emerged as Secretary of State James A. Baker III prepared a major address that aides said will outline a new Administration approach to its transformed former adversary, including programs to control nuclear weapons.

In advance of the speech, to be delivered today, the Bush Administration on Wednesday issued an unusual statement of confidence in the Soviet armed forces’ nuclear command, saying that its control over the Soviet Union’s 27,000 nuclear weapons is reliable and safe.

“We remain confident that the weapons are secure,” State Department spokeswoman Margaret Tutwiler said. “Soviet Defense Minister (Yevgeny I.) Shaposhnikov stated that the weapons are still under the control of the Soviet army, which has detailed procedures for ensuring the safety and security of the weapons.”

A senior official said the statement was based on the latest U.S. intelligence assessments of the situation within the Soviet nuclear force. The statement, which appeared designed to address public fears in the United States, went to the most frightening of all the Soviet Union’s problems: the prospect that nuclear weapons could fall into the hands of rogue commanders who might use them--or sell them to other countries.

Earlier in the day, President Bush told reporters that U.S. officials are watching the control of the Soviet arsenal “extraordinarily closely” and that he had received “pretty good” assurances. “I see no reason to alarm the American people,” he said.

As the Administration continues to confront the disintegration of the Soviet nuclear superpower, State Department officials said that Baker now hopes to extract specific commitments from leaders of newly independent republics to abide by U.S.-Soviet arms treaties.

That task, described as a top priority for Baker’s visit to the region this weekend, provides a further sign of the new attention the Administration plans to devote to Yeltsin and other republic leaders.

Administration officials described that focus as an indication that the United States is now resigned to the fact that pacts signed only with Moscow may now have little relevance.

To pave the way for relations with members of the new Slavic commonwealth formed over the weekend, top Baker aide Dennis Ross met this week at the State Department with representatives of the alliance’s founding republics: Russia, Ukraine and Belarus, sources familiar with the unannounced sessions said.

And Strauss, asked after addressing the House panel to assess Gorbachev’s position, said that the Soviet leader “has no power base any more,” adding bluntly: “Yeltsin has it.”

That frankness was in sharp contrast to the caution of the Administration’s public position. Asked Wednesday morning whether the balance of power has now tilted toward Yeltsin, White House spokesman Marlin Fitzwater declined to answer and said the United States will simply “wait and see how this sorts itself out.”

Times staff writer Michael Ross contributed to this report.