Something like:
Moscow Falls.
Stalin resolves to stick it out to embolden the Russian people, but instead he dies in a last ditch evacuation attempt as one Otto Skorenzy manages to shoot him dead.
The Soviet Politburo had been pressured into sticking with Stalin--they too are largely captured, killed, or left with only minor figures still alive.
Despite this disaster, the Russian People can not surrender to the German Forces--the Soviet Government may have cracked--but Germany is making a war of race and at this point the Soviet Union gives up all pretensions to communism. The quickly assembled and extremely desperate leadership will strike any deal with any nation to keep their people alive--and this means things like Alexandr Kerensky being summoned, as well as an Emergency Government--a government made of communists, nationalists, reformers and above all else, desperate people out to avoid being put on the chain by the Nazis.
By 1946, the Germany invaders have been crushed. American Nuclear Weapons have stained the strikes over Germany a blood red, and its landscape a coal black.
But what government is left? The Emergency Government was a power-sharing arrangement forced on the Soviet Union in a time of great need and included most of the opposition forces. That said, the Communist Faction is in a very bad position in terms of negotiations--Stalin's victims were legion and perhaps most unforgivably, Stalin's leadership of the war was a disaster.
Thus, in 1946-8, the Communists find themselves marginalized as the new Government agrees to accept American Aid through the Marshall Plan--an arrangement that keeps the Communists down for good, as Russia stumbles with a military dictatorship.