German unification and its impact on Europe will dominate the political agenda of the Washington summit, eclipsing arms control and other bilateral Soviet-U.S. issues that have been the center of past summits, U.S. and European officials predicted yesterday on the eve of Mikhail Gorbachev's arrival here.

The only topic likely to get as much time and attention as Germany during the meetings between President Bush and Soviet President Gorbachev will be Gorbachev's mounting troubles back home, a senior U.S. official told reporters and editors of The Washington Post yesterday.

For Bush, the dominant role of German issues at this summit represents a vindication of a decision he made shortly after coming to office to center his European diplomacy on strengthening the U.S.-West German relationship.

For Gorbachev, West Germany has moved in the past six months from being a potential economic savior for the Soviet Union to being an intense political problem that if mishandled could bring about his downfall.

Gorbachev is vulnerable today to being accused of having "lost" East Germany to the West.

At the same time, the Soviet leader still needs West German economic help.

Bush will suggest to Gorbachev new security arrangments in Europe that should "ease the appearance of the U.S. winning" a major victory through the collapse of Soviet control in East Germany, the senior U.S. official indicated.

The high priority Bush has given to supporting Bonn in international negotiations and to making sure that U.S. policy choices do not undermine the reelection chances of the center-right coalition government led by Chancellor Helmut Kohl have caused some irritation in Paris and London. British and French diplomats have told American officials that Washington's preoccupation with supporting Bonn to the hilt was distorting the rest of U.S. European policy.

The German focus of the Washington summit is likely to rekindle concern in other European capitals about the long-term effect of unification on the continent.

But the remarks by the senior U.S. official yesterday made it clear that working with Gorbachev and with the Kohl government to redraw "the political map" of Europe remains Washington's top priority, a point that should emerge clearly in the summit conversations.

In working out the new military and political balances in Europe, "we not only have to deal with the Soviet Union, we have to try to deal with Germany," the senior U.S. official said, " . . . to support German unification unreservedly. We are the only ones who have not showed any kind of queasiness about it. To give Germany the feeling we're behind them, we believe in them."

The Bush-Gorbachev conversation is expected to concentrate on the narrow issue of a united Germany's membership in the North Atlantic Treaty Organization and its military command, a goal that Kohl and the East German government have both accepted publicly under the prodding of the Bush administration.

The Soviets say they strongly oppose such a step.

Bush stands firmly against the idea of Germany taking up political membership in NATO but staying out of its military command, the U.S. official said. Gorbachev seemed to offer this as a possible compromise in a press conference in Moscow last Friday.

Saying that the Soviets should not want to change the current situation, in which West German army units fall under NATO control rather than national control, the senior official pointed out that taking Germany out of the military command might also encourage the Germans to seek nuclear weapons. "But there are other things we could do," the official added.

Gorbachev appeared to gain some new support, however, from French Foreign Minister Roland Dumas, who said in a radio interview in Paris that he understood why Gorbachev was opposing a reunited Germany's membership in NATO.

"The request concerning the security of the Soviet Union is in my view legitimate," Dumas was quoted by the Reuter news agency as saying in the interview on the Europe-1 network. "It is the duty of the West to address this concern. If we do not find a proper solution within a reasonable period of time there is a threat of crisis or tension between East and West."

Dumas accompanied French President Francois Mitterrand to Moscow last Friday and is close to West German Foreign Minister Hans-Dietrich Genscher, who has not voiced as clear a position on German membership in NATO's military structure as Kohl has.

While Dumas' statement stopped short of saying the West should reconsider its insistence on German membership in NATO, his emphasis on meeting Soviet concerns is likely to raise questions in Washington and in Bonn about the French position.

Gorbachev is expected to seek from Bush fresh assurances that the United States will not put restrictions on Moscow's expanding trade and financial relations with Bonn, which is already the principal economic partner in the West for the Soviets.

With unification, Bonn will inherit factories and businesses in East Germany that account for a major share of the Soviet Union's total foreign trade.

The West Germans will have to provide the capital and technology to keep these factories in business for the Soviet market, or replace their output with goods and services from the West.

A unified Germany and the Soviet Union are considered almost certain to seek a bilateral treaty that will regulate economic cooperation, a prospect that causes no concern in Washington. But suggestions in Bonn that a German-Soviet bilateral agreement on security questions will follow unification appears less welcome here.