During the 2063B.S winter Madhes rebellion, Mahantha Thakur was the minister. After the success of the second people's movement, the chairman of Nepali Congress, Jirija Prasad Koirala became the prime minister.
Mahantha was a senior minister in Koirala’s cabinet. Mahantha, a senior minister of the Nepali Congress, did not only resign from his ministerial post ahead of the ‘64 constitutional election. He left the Nepali Congress.
With an intention of leading a Madhes-based politics, he formed the Terai-Madhes-Democratic Party(Ta.Ma.Lo.Paa) and took part in the parliament with the same.
Later when he teamed up with various factions of the Sadbhwana Party and established the National People’s Party/Rastriya Janata Party (Raa.Ja.Paa), Mahantha became the chairman again. In actuality, although there were 6 parties that were Madhes centered in the Raa.Ja.Paa, everyone agreed on the leadership of the experienced Mahantha.
In 2077B.S, the Upendra Yadav led Socialist Party and the Mahantha Thakur led National People’s Party unified and formed the People’s Socialist Party(Ja.Sa.Paa). A year after that, Mahantha Thakur left the party and formed the Democratic Socialist Party(Lo.Sa.Paa). Mahantha Thakur is the chairman of the said party and its election symbol is “cycle”.