With Trotsky mostly on the sidelines through a persistent illness, the Zinoviev-Kamenev-Stalin triumvirate collapsed in April 1925, although the political situation was hanging in the balance for the rest of the year. All sides spent most of 1925 lining up support behind the scenes for the December Communist Party Congress. Stalin struck an alliance with Nikolai Bukharin, a Communist Party theoretician and "Pravda" editor, and the Soviet prime minister Alexei Rykov. Zinoviev and Kamenev strengthened their alliance with Lenin's widow, Nadezhda Krupskaya, and also aligned with Grigori Sokolnikov, the People's Commissar for Finance and a candidate Politburo member. Their alliance became known as the New Opposition.