It's a well documented fact that Lenin never chose a successor, Trotsky was too radical and Stalin was seen only as a necessity during the violent revolution that lead to the communist accent to power in Russia. Stalin's rise to power will not be a peaceful one and will eventually end up costing the lives of most of his political opposition, any opposition that isn't killed in the time immediately before and after Stalin's power grab then they will most likely be murdered later in the 20th century. Thus is the life of a leftist.
Stalin was appointed be Lenin as the party secretary, a
seemingly harmless position that seemed only to require a
rudimentary knowledge of politics, the kind that Stalin had.
Lenin did not anticipate that Stalin would use this position
to his advantage, allowing only his devout followers into
the upper echelons of the communist party, though they were
few at first, Stalin's cronies quickly set about slandering
his opponents, calling the Trotsky and the other members of
the Menshevik party anti-Leninists and their reforms to
conservative. Surprisingly The Triumvirate as the Stalinist called themselves usually agreed with Stalin but also
resorted to these radical means in a hope to consolidate a position in the party if Stalin did succeed in taking power after Lenin's inevitable demise.
Lenin frequently condemned Stalin, and harbored the opinion that neither Stalin or Trotsky should inherit the title General Secretary from him. Late in his life Lenin wrote letter to the Politburo that harshly ridiculed Stalin and his new position as General Secretary, and suggested that he should be replaced before he could gain a greater following. Since Stalin had essentially gained ultimate power he could use it to delay the reading of this note and other like it. All history of Lenin'bs distrust for Stalin was also erased and a secret propaganda campaign was set in motion to change the history of the revolution. Stalin was photo shopped into many pictures with Lenin and they were often made to look like good friends. Trotsky was frequently taken out of photos and Stalin would replace him, thus eradicating any doubt that Stalin had always been Lenin's right hand man.
After rewriting Russian history with himself as Lenin's chief advisor and primary abettor he was able to ride the Lenin Wave. Since Lenin was seen as the father of the revolution there was no better way to consolidate power in Russia than to b seen as a one of Lenins innermost executives, being a figure of great standing in Lenin's eyes was to be one in Russia's eyes. Stalin knew this and took advantage of it, often leading funerals while standing over Lenin's embalmed body. Soon people began to believe that Stalin was Lenin's chosen successor. The number of people publicly questioning Stalins motives took a sharp decline, not only because of the "cult of personality" that had recently formed around both Stalin and Lenin, but also because of the killing and ostracizing that came with disagreeing with either of their methods.
Historians are still baffled by certain occurrences in the instigations of communist power in Russia. Occurrences such as; how was it that the Bolshevik revolution was victorious; how did communism flourish for so long in a country that was still centered on agriculture; And how did Stalin succeed Lenin? Russia was not ready for any of the points listed, but through means of brutality and cut-throat politics all such factors occurred. It is suffice to say that Stalin killed his way to the top.