When 20 rebel Trinamool Congress Lok Sabha MPs decided to abandon Mamata Banerjee's parliamentary fold, many expected them to take the familiar route travelled by the majority of defectors from various political parties across the country over the past decade -- join the BJP.

Instead, they chose the Nationalist Citizens Party of India (NCPI), an obscure Tripura-based registered unrecognised political party whose political insignificance may well have been its biggest asset -- providing the rebels a legally safer route out of the TMC while allowing the BJP to benefit from their support without immediately inducting them.

A little-known political outfit that fielded four candidates in the 2023 Tripura assembly elections with the slogan "reject political turncoats to save your rights" was catapulted into national limelight on Sunday after a rebel faction of the Trinamool Congress comprising 20 Lok Sabha MPs announced its merger with it.

Records show that the Nationalist Citizens Party of India (NCPI), the party in question, had eventually contested three seats - Chawamanu, Ambassa, and Kailashahar - in the 2023 Tripura polls, with its candidates finishing either behind NOTA or securing only a few votes more.

The nomination of Rita Shil Halam, who was fielded by the NCPI from Karamchara, appeared to have been rejected after scrutiny.

The decision of the rebel TMC faction to merge with the NCPI on Sunday may appear puzzling at first, but political observers believe it's a careful move to bypass legalities and, at the same time, make political calculations, underpinning the biggest crisis to have hit the TMC since its formation in 1998.

The choice of NCPI appears to offer something the BJP could not -- a legally defensible pathway out of the TMC while preserving their collective strength in Parliament.

The rebels' original plan was simpler: walk out of the TMC parliamentary party with two-third MPs, constitute a separate group in Parliament and support the BJP-led NDA, sources said.

But parliamentary rules left little room for such an arrangement. Faced with that legal hurdle, they turned to the NCPI, which offered what a standalone rebel bloc could not: legitimacy.

A senior rebel MP said the decision was driven by "practical considerations rather than ideology".

"We wanted to move collectively and create a political space outside Mamata Banerjee's control without triggering unnecessary procedural hurdles. The NCPI route offered a workable parliamentary solution," he said.

CPI(M) leader Sujan Chakraborty believes the move reflects lessons drawn from the parallel rebellion inside the West Bengal Assembly.

"This is less of a political merger than a legal device," he said, arguing that the Lok Sabha rebels seem keen to avoid the complications that followed the TMC split in the Assembly.

The contrast is striking. In the Assembly, dissident legislators sought to project themselves as the authentic voice of the TMC. They elected their own leader and challenged the authority of the party's official leadership. The result was immediate litigation and competing claims over legitimacy.

Senior TMC leader Sougata Roy dismissed the significance of the development, insisting that the party's strength remained intact.

"Some MPs may leave, but the Trinamool Congress belongs to Mamata Banerjee. The organisation, workers and people remain with her. Those who think they can weaken the party by changing labels are mistaken," Roy told PTI.

Many among the rebels spent years attacking the BJP and contesting elections against it. While their support in Parliament strengthens the NDA's legislative position, their wholesale induction could create friction within the BJP's Bengal unit, where local leaders have built their politics in opposition to them.

Incidentally, NCPI's registered address is in West Bengal's Howrah, with one Sheuli Kundu, who calls herself an advocate practising in the Calcutta High Court, listed as its president.

Its Chawamanu candidate, Barjeda Tripura, who secured 536 votes in the election, was surprised when PTI contacted him on Sunday following the merger announcement.

"I contested in 2023. What has happened three years later now?" he asked, expressing disbelief after being told that a group of Lok Sabha MPs had joined the party that had fielded him.

Barjeda said he was a daily wage labourer. "In 2023, a person called Krishna Debbarma had reached out to me about elections. So I contested. Many years ago, I was a supporter of the Congress," he told PTI.

Congress leader Adhir Ranjan Chowdhury sees the development as an exercise in parliamentary pragmatism.

"The BJP's immediate interest is numbers in Parliament, not necessarily expanding its organisational family in Bengal overnight," he said.

Political analysts argue that the NCPI route solved two problems simultaneously -- it gave the rebels a vehicle through which they could move collectively without immediately confronting legal complications and allowed the BJP to secure parliamentary support without forcing an awkward political merger in West Bengal.

"It is easier for the BJP to work with them as allies for now than absorb them immediately into the organisation," political analyst Biswanath Chakraborty said.