On 5 September 1925, Sokolnikov signed the unpublished 'Platform of the Four', a joint protest by Zinoviev, Kamenev, and Lenin's widow,
Nadezhda Krupskaya against Stalin's leadership. His decision seems to have been more personal than political, because politically he was on the right of the party, whereas Zinoviev and Kamenev were about to join Trotsky in the
United Opposition. He appears to have been motivated by mistrust of Stalin, and friendship with Kamenev. Even while publicly aligned with the opposition, he continued to argue that agricultural output had to be increased before industry could be expanded, and that consumer goods should be imported to give the peasants an incentive to take their produce to market. He was also openly dismissive of the figures produced by
Gosplan, believing that 'state capitalism' properly managed would be more efficient that a centrally planned economy. According to historian, Hiroaki Kuromiya, Stalin pleaded with Sokolnikov, not to discuss Lenin’s testament at the
15th party Congress. In October 1926, the six principal leaders of the opposition, including Sokolnikov, signed a promise to follow the party line in future. He kept to this line, unlike the others but was removed from the Politburo nonetheless, in January 1926, while being allowed to retain his membership of the Central Committee. In the same month, he was removed from the post of People's Commissar for finance, and appointed Deputy Chairman of Gosplan, despite his well known scepticism about the value of central planning. In spring 1926, he was sent on a trade mission to the US, which aborted when he was denied a visa. In March 1928, when the Central Committee discussed the food crisis – to which Stalin reacted later in the year by sending shock troops into the villages to collect grain by force – Sokolnikov made a speech in which, while admitting that he had been wrong in the past, he stuck to his earlier beliefs by arguing that the way to get peasants to sell their produce was to raise the price of grain. However, after the introduction of the
First five-year plan, he defended the principle that it was possible and necessary for the state to intervene and plan economic output. He wrote: In July 1928, Sokolnikov and Bukharin were returning to the Kremlin from a Central Committee plenum when they encountered Kamenev, and Bukharin talked indiscreetly about the gathering opposition to Stalin within the Politburo. In February 1929, Sokolnikov was formally rebuked by the Politburo for being present during this conversation, after a transcript had been published abroad. He was removed from his post in Gosplan. From 1929 to 1932, Sokolnikov was the Soviet
ambassador to the United Kingdom, where the newly elected Labour government had extended diplomatic recognition to the USSR. Speaking very little English, he had limited contacts with leading British politicians.
Beatrice Webb who invited Sokolnikov and his wife to her home and introduced him to the Chancellor of the Exchequer
Philip Snowden noted in her diary: “We are the only ‘Cabinet’ members who have consorted with them. The
Hendersons do not ‘know them’ socially, nor the
PM." In 1932, Sokolnikov was recalled to Moscow (and replaced by
Ivan Maisky, who spoke fluent English) and appointed Deputy People's Commissar for Foreign Affairs. == Arrest and execution ==