However, the mautam (bamboo famine) of 1958 and its protégé insurgency in 1966 downgraded its status, so that the party was compelled to dissolve in 1974 and merged with the Indian National Congress.
However, the Mizo leaders, especially the central organisation Young Lushai Association (YLA), preferred complete independence from India and started a boycott against British orders.
This was largely because of the general anachronistic attitude towards tribal chiefdom and their British allies, who wearied them with levies and forced labour.
The intellectuals mounted a coup in the party's first general meeting on 24–26 September of that year, which led to the resignation of Pachhunga and elimination of other leaders.
The issue erupted in the November meeting, and an election in early 1947 clearly toppled Lalhema, who was ousted by Khawtinkhuma, a fresh master's degree holder from Tripura.
This for a time formed a public and religious chasms in Aizawl as the Mizo Union was supported by the educated class and commoners and also mostly by church leaders.
In early 1947m Khawtinkhuma was offered a regular government job and was succeeded by Pastor Zairema, who was supported by the Presbyterian Church, on 18 January.
When the Mizoram District Council was created by the Government of India, the first general election in April 1952 was cleanly captured by Mizo Union (17 out of 18 electorates), and President Lalsawia became the first Chief Executive Member.
The ever-strategic Saprawnga declined and unexpectedly returned to the Mizoram District and cast a motion of no confidence against CEM Lalsawia, whom he eventually replaced.
The original aspiration of sovereignty was immediately subdued, and the attempt for unification of all Mizo tribes into a united state was a total failure.
Instead, the party was more and more engrossed in the Indian politics to the disappointment of many, whuich was one of the basic factors of the rise of Mizo National Front and the eventual uprising.
The shortcoming was compounded by the 1959 famine, as the ruling party was held incapable of solving the socio-economic crisis, and was accused of indifference towards the suffering of the people.
The original bearing "Common" was expressly clear that it was a force to overthrow the oppressive tribal governance of the chiefs, which was further exploited by the British.
However, the Mizo Union Council, which had turned to patronise the tribal chiefs, warned them of physical opposition to such protest march even to the extent of taking up arms, and the rally was called off for fear of bloodshed.
The party convention on 10 June 1963 made a resolution to demand for a Mizo state, which should include all Mizo-inhabited areas of Lushai Hills, Tripura, Assam and Manipur.