And then came Narendra Modi, and the BJP reinvented itself into an election machine. And it has firmly set its sights on winning the entire Northeast region, both for ideological reasons as well as to offset any losses in North India in 2019. When this BJP met the formidable CPM in 2019, it was a landslide - it increases its vote share to 43%, completely taking over the Congress' share. The Grand Old Party of India was left with a royal duck, its third since 2014 after Andhra Pradesh and Delhi, in a state where it once was the ruling party. That's the extent to which the party has collapsed, even if it is in such a small state.
But the BJP did even better than simply gobble up the Congress' votes. It smartly partnered with the IPFT and took a major chunk of the tribal votes that were once guaranteed to the CPM. It was these two things combined that put it past the 2/3 majority in the Agartala House. This partnership was by no means easy or natural - the BJP is completely against dividing the state, which was one of the key planks of the IPFT that differentiated it from its rival, INPT. But hard work from BJP members as well as RSS volunteers eventually sealed the deal to push the hegemonic Left out of the state.
Although on a much smaller scale, the BJP has become only the second party in the country's history, after the TMC, to unseat a dominant Left government (they never really enjoyed that kind of dominance in their original bastion, Kerala). It is also a historic opportunity for the party to bring Tripura into the mainstream of India, through infrastructure and industrialization that the state badly needs. The people of Tripura, having grown up under the CPM for an entire generation, took a lot of risks to elect the BJP. The test has just begun.