Stalin gained the advantage of organizing Lenin’s funeral, to prove he was a real communist and to show his loyalty to Lenin by saying in his speech: “In leaving us, Comrade Lenin commanded us to keep the unity of out Party as the apple of out eye. We swear to thee, Comrade Lenin, to honour thy command.”(Stalin’s speech line 4-6) One thing that helped Stalin to rise to power was Trotsky’s absence, this showed everybody that Trotsky did care about he did not have respect for Lenin’s memory, and it raised many doubts about him. Later on he declared that Stalin gave him the wrong date of the funeral, but this excuse sound childish, and the curious thing is that Trotsky could really have done such a thing because he was very arrogant so for some reason he did not want to pay the last tribute to Lenin. The support from the people was also an important factor for the Stalin’s success. Coming from a poor family he could easily understood the needs of the poor people. Trotsky instead was the son of a well off landowner who showed to have a great intelligence and very good military skills; clearly showed in the arrangement of the Red Army in order to defend the revolution. So Trotsky was not a real politician; Stalin looked more suited for the top job because he was very close to the poor people, he was though he was a strong man who could control the whole state.
For the rest of 1924 the Politburo continued to argue about the future of the Soviet economy. The strongest argument was between Stalin and Trotsky over Trotsky's theory of Permanent Revolution.
Trotsky thought that communism was meant not to stay in the USSR only; he argued that the other countries feared communism and they would try to destroy it. For this reason, he said, it was necessary to spread communism to the countries as well. This would be done by giving help to revolutionary groups and parties already present into these countries.
Stalin came up with the theory of Socialism in One Country. He said that they should focus on the USSR only. The rest of the world would come later. The Communists should concentrate on building up the economy of the USSR, not waste money on helping revolutionary groups abroad. With a strong and modern economy, the other countries would never attack USSR.
It was also said that Trotsky and Bukharin should lead the party as well. Probably the reason why it was not published was due to other personal problems related to Trotsky and the others members as well. At the end Trotsky lost the propaganda war, so he lost much power as well, not only in the Politburo but in the Central Committee as well. So he was dismissed of the position of Commissar of War.
So with Trotsky weakened Stalin now had to deal with two powerful characters, Kamenev and Zinoviev. In 1925 Zinoviev wrote about leaving the NEP (New Economic Policy), restriction for peasant and, enforce industrialisation, gave Stalin the pretext to leave the triumvirate and sign an alliance with the right wing of the party lead by Bukharin. In response to that Kamenev, Zinoviev, and later on Trotsky formed the “New Opposition” or “The United Opposition”. After the lost of power of Trotsky, Kamenev and Zinoviev gained much power and they had more or less the same ideas of Trotsky, so they decided to join the forces against Stalin and right wing of the Communist party.
However the New Opposition was defeated by Stalin and his new supporters, thanks at the great power that Stalin had in his hands. Kamenev and Zinoviev were dismissed from their posts of Soviet Chairmen, and replaced with two Stalin’s supporters Molotov and Kirov.
In 1927 Trotsky tried to gather as much support as he could to beat Stalin, but he completely failed his aim, and with the Congress consent he was expelled from the party.
After the defeat of Trotsky now Stalin decided to get rid of the new allies as well, he came out with a new economic policy “the five years plan”. The right had basically two problems, one was ideological, because keeping the NEP would have been going against the communist ideology; the other one was the organization. Stalin took the advantages of their difficulties and defeated them. So in 1929 Bukharin, Rykov and Tomsky were dismissed, and Stalin remains as the only survivor and took the lead of the USSR.