I was tumbling down the Wikipedia link hole, and I came to an article about the Bolsheviks; I saw this excerpt:

In 1952, at the 19th Party Congress, Stalin declared: "There are no more Mensheviks. Why should we call ourselves Bolsheviks? We are not the majority, but the whole party." According to his suggestion, the Bolshevik party was renamed the Communist Party of Soviet Union. Since that time, the term Bolshevik has been regarded as obsolete, and relevant only to the pre-Revolutionary times, during the Russian Revolution itself and the Russian Civil War which followed.

Was this a trial in front of their Congress, or did he hold a position of power still?