Rahapal, a frontline leader of the GJM since its inception in 2007, joined the ruling party at a programme at Gairibas in Kalimpong subdivision yesterday.
"During the Gorkhaland movement, Bimal Gurung kept on saying they did not want GTA but a separate state. But they ditched the people by accepting the GTA Sabha and got their family members and relatives elected to the autonomous body," Rahapal claimed.
"My decision to resign from the Morcha and join Trinamool is a protest against the undemocratic functioning of the hill party," he said.