What were the main reasons for the emergence of new political parties in the USSR in the late 1980s?

First, the 6th article of the constitution was canceled, which made the formation of new parties in our country legal.
There was a fairly large layer of middle-level party leaders who had many ambitions, but in the Communist Party they were still very far from taking top positions.
Among those whom we call the intelligentsia there were many dissatisfied with the country’s leadership. These people had their own (sometimes quite radical) views on which way the state should develop.
The popularity of separatist ideas has sharply increased, including among the national elites.