These are the main political parties in Tanzania. It used to be CCM vs NCCR Mageuzi between 1995 and 2005 before things changed. Also, CUF used to be the third most powerful party before 2015 when it crumbled giving way to ACT Wazalendo. CCM vs CHADEMA dominance is expected to last for a long time probably for decades as it is in the United Kingdom for Labor party vs Conservative party.
These parties have dominated UK politics for about 200 years. If CCM lose in the coming elections, that might throw the old party to the 3rd position and mark the end of six decades of CCM domination of Tanzanian politics.