The Soviet campaign to cast doubt on the dependability of the U.S. is in full bloom across Europe, particularly here in West Germany, which for 30 years has been the root of U.S. European strategy against Moscow.

The swell of this Soviet campaign is everywhere, sweetened with the apprehensions of America's NATO allies as to whether the Carter administration really knows what it wants and how to get it.

The Soviet ambassadors and their ample staffs here and in East Germany tirelessly contrast the serious nature of Soviet policies with the erratic political style of President Carter, following the disillusionment of Vietnam and Watergate.

What distinguishes this Soviet propaganda campaign is President Leonid Brezhnev's surprising efforts to find an audience among the bad old car-war warriors of the German right - like Franz Josef Strauss. These are the leaders of the Christian Democratic Union (CDU) and Christian Social Union (CSU), parties that for the past decade have been in the opposition to the Social Democratic Party now under Chancellor Helmut Schmidt.

During his visit to Bonn in May, Brezhnev went out of his way both to admonish and to court Helmut Kohl, the CDU leader, Kohl being the top opposition spokesman, it wasn't all that unusual for him to be received by Brezhnev for a 45-minute lecture about the CDU's alleged anti-Soviet tendencies.

But Strauss was a different number. Strauss has held a special place in the Kremlin's heart ever since his first election to the West German Parliament in 1949, a German revanchist feared and attacked by the Kremlin as a latter-day Attila the Hun. Yet it was with Strauss that Brezhnev exerted his charms to a greater degree than with any other German leader.

Strauss is one of the smartest politicians in Europe, and a sly, witty debater of great force and positive views. He listened while Brezhnev read a prepared statement rebuking revanchism and appealing for the conservative's support for Soviet-style European security. Strauss replied bluntly.

He described himself as having only one policy for Germany - the same policy proclaimed by Talleyrand for defeated France at the Congress of Vienna in 1815: rescue for France whatever can be rescued after the collapse of Napoleon.

There was blame enough to go around for Hitler's conquests, said Strauss, and a large share of it was the Stalin-Hitler non-aggression pact of 1939, which removed the last obstacle for Hitler's wars.

Strauss then told Brezhnev that a conflict is in the making in Africa, an explosion that could exceed the point of no return and lead to a worldwide war.

From Brezhnev came no harsh response. Brezhnev listened, then insisted - over Soviet Foreign Minister Andrei Gromyko's visible annoyance - on walking outside with Strauss and seeing him to his car.

That was unprecedented treatment for Strauss who, despite three decades at or near the pinnacle of West German politics, has never heen invited to the Kremlin. Brezhnev was praised in the controlled Soviet press for having tamed and charmed cold warrior Strauss and - at least for now - 30 years of anti-Strauss invective disappeared from the Soviet press.

Brezhnev's point in courting Kohl and Strauss seems obvious: First, to feed them the suspicioun that dependence on Washington is a long-range gamble that may not pay off: and second, to emphasize that Moscow's will and determination will never change - and had better be taken into account.

Such Moscow-inspired atmospherics have clearly had an effect on Chancellor Schmidt, who is burdened with a virulent left wing. Without clear U.S. leadership for West Germany and other European states, Schmidt will hardly say anything nasty about Soviet adventures in Africa, Afghanistan, South Yemen of elsewhere.

Uncertain of elusive American leadership, Schmidt for good reason chooses to risk no offense to the Kremlin.

Kohl, Strauss and the conservatives, with the luxury of being out of power, have no inhibitions - today - about offending the Soviets, and no doubts about reasons for doing so. But Brezhnev's subtle dialogue, craftily woven into his speech in Minsk last week, suggests that he may see a change coming. If it does come, it will be pushed forward by worldwide Soviet propaganda about dependability and steadiness of Soviet world policies. But it will be triggered by something else: the perception that Jimmy Carter's Washington either does not understand the game or is too tired to play.