What countries have a Communist Party in the somewhat majority?

All I know is that Russia and maybe China has it. Any more?

None.

When a government closes the elective process, controls the police, military, the media and doesn't allow anyone to speak or publish criticism of the leadership, their power is no longer based on majority rule.

In the countries that skyDancer lists, only a very small percentage of the population belongs to the ruling party. Even at the height of the Soviet Union's power, fewer than 25 percent of the people in those countries were members. Less than six percent of the world's population are active members of communist organizations today and those numbers are declining.

The largest population living under communism is of course China but their economic system is changing to capitalism and the communist social system has severely declined since Chairman Mao's death so only the political agenda remains. Only six percent of the chinese are members of the Communist Party.

China, Cuba, Laos, Vietnam, and North Korea have communist governments. To be technical, they've got the "majority" of the political power. For maps, see: http://en.wikipedia.org/wiki/Communist_state