I'm going to disagree with assertions that Kamenev and Zinoviev would agree to a ruling coalition with Bukharin. The issue is that Kamenev and Zinoviev were ideologically close to Trotsky even though they hated his guts as much as just about the rest of the Bolsheviks, and they fundamentally disagreed heavily with Bukharin about economic and social policy. The NEP is a strong example, particularly in the power struggle after Lenin's death and Trotsky's expulsion - whereas Kamenev and Zinoviev wanted to be rid of it because it wasn't ideologically sound, the Right wanted to keep it because it worked. If Bukharin was going to enter a ruling coalition with anyone, it would have been with figures like Rykov and Tomsky, who had previously served in pretty strong positions within the Soviet government.