Marthon Sangma, the legislator from Mendipathar in North Garo Hills district, and Jimmy D Sangma, MLA from Tikrikilla in West Garo Hills district resigned from the assembly membership prior to joining the NPP. In November 2021 led by former chief minister Mukul Sangma, 12 out of the 17 Congress MLAs had submitted a letter to the speaker, announcing their merger with West Bengal chief minister Mamata Banerjee-led Trinamool Congress.