 Complete the following phrase:  In early 1920, Medvedev went to Moscow to work in the central committee of the All-Russian Union of Metalworkers. Together with Alexander Shlyapnikov and others, he participated in the Workers Opposition, a tendency of the Russian Communist Party, which called for worker initiative in managing the economy and for working-class members to prevail in leading organs of the Communist Party. At the Tenth Party Congress of 1921, however, internal factions were banned and the Workerss Opposition was dissolved with immediate effect, even though Medvedev was elected a candidate member of the Central Committee. In February 1922 he was a signatory of the so-called Letter of the 22, whereby several former members of the Workers Opposition and other party members of working class origins appealed to the 1922 conference of the Comintern Executive against the undemocratic internal practices in use within the Russian party. At the subsequent 