AH Challenge Bukharin wins in the power struggle

The Struggle for succession after Lenin died wasn't a simple struggle between Trotsky and Stalin.

There were other players such as Zinoviev and Kamenev as well as Bukharin.

One of many reasons Stalin won was because he had many key positions in the politburo, which included the title of General secretary.

Yur challenge, should you accept it, is to find a way for Nikolai Bukharin to win the struggle.
 
Trotsky dies in a way that gets Stalin blamed (deranged supporter of Stalin acting on his own? Stranger things have happened, maybe), Stalin loses a great deal of influence, maybe even forced into exile, Bukharin outmanouevres the remaining major opponents to him being the Top Guy (Trotsky and Stalin being effectively out of the struggle)?
 
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