With Trotsky largely marginalized, Zinoviev and Kamenev had a falling out with Stalin at the XIVth Communist Party Conference in April 1925 over Stalin's October 1924 proposal of "Socialism in One Country", which Zinoviev and Kamenev now openly opposed. By this time, the Right Opposition leader, Bukharin, had elaborated on Stalin's socialism in one country policy, giving it a theoretical justification. This solidified the Right Opposition as Stalin's main allies, as the "triumvirate" of Stalin-Zinoviev-Kamenev from recent years broke up. Soon after the April 1925 Conference, Zinoviev and Kamenev formed the New Opposition, but they were defeated by Stalin, who was again supported by Bukharin and Rykov, at the XIVth Party Congress in December 1925. Soon after their defeat at the Congress, Zinoviev and Kamenev joined forces with Trotsky's Left Opposition in early 1926, in what became known as the United Opposition. From July to October 1926, the United Opposition lost out to Stalin, and its leaders were expelled from the ruling Politburo.