What was the role of the Communist Party in the Soviet Union's governance?

It ruled for over 70 years and was not accountable to the people.

The Communist Party ruled the Soviet Union for over 70 years and was not accountable to the people.
The Soviet Union had become stagnant in an administrative and political sense as well. The Communist Party that had ruled the Soviet Union for over 70 years was not accountable to the people. Ordinary people were alienated by slow and stifling administration, rampant corruption, the inability of the system to correct mistakes it had made, the unwillingness to allow more openness in government, and the centralisation of authority in a vast land. Worse still, the party bureaucrats gained more privileges than ordinary citizens. People did not identify with the system and with the rulers, and the government increasingly lost popular backing.