The line-up for the Nagaon parliamentary seat byelection on October 6 is complete with the All India United Democratic Front (AIUDF) nominating its chief, Badruddin Ajmal, as its candidate on Tuesday. His entry makes it a four-way contest, with former legislator Sibamoni Bora of the Congress, former bureaucrat Devasish Sharma of the BJP and academic Abdul Salam of Trinamool Congress also in the fray.

Nagaon is the first major face-off between the principal combatants, BJP and Congress, since the former’s crushing sweep in the April Assembly election with 102 out of 126 seats for the National Democratic Alliance. The AIUDF’s last-minute candidate switch from former student leader Rejaul Karim Sarkar to its founder is a bold gambit that could radically alter Opposition politics in a foreseeable future where the ruling party holds near-absolute sway.

Even as the upper regions of Assam were still reeling from the impact of sudden floods in July, the State’s broader Opposition unity fractured on September 3 when the Congress formally severed ties with Akhil Gogoi’s Raijor Dal. Wazid Ali Choudhury, Leader of the Opposition in the Assembly, said the decision by the Congress leadership followed repeated criticism of the party by its ally. “Akhil Gogoi has constantly been criticising the Congress party and its leaders. We got tired of the fact that he was in an alliance with us and still criticising us,” he said. The erstwhile junior ally chose to train its guns on Lok Sabha MP and Assam Congress chief Gaurav Gogoi, questioning the scale of his engagement with the flood crisis.

While he opted not to put up a candidate in Nagaon in the interest of “preventing the rise of communal forces”, the Raijor Dal chief is eyeing a larger chunk of the Opposition space over the full term of the BJP-led government. The party won two seats in the April election, Mr. Akhil Gogoi defending his Sibsagar seat from 2021 and Mehboob Muktar winning Dhing LAC in Nagaon Lok Sabha constituency.

It could have added a third to its kitty, but the Congress’s veto forced Raijor Dal to drop Sherman Ali Ahmed as its candidate from Mandia; Mr. Ahmed promptly walked over to the Trinamool Congress and secured the party its sole seat.

Raijor Dal’s long game

With only one non-Muslim among the Congress’s 19 winning candidates, the Raijor Dal’s long game is clear: expand at the expense of the principal Opposition party among the Assamese Hindu voters, a prospect even Chief Minister Himanta Biswa Sarma had predicted in February this year.

The Muslim vote isn’t a settled question either. The Congress wrested back much of this electoral constituency from the AIUDF in the last Assembly election after refusing to renew its tie-up from 2021, but dismal performances across seats with a thin minority concentration leave it vulnerable to another shift. Mr. Ajmal set the cat among the pigeons as early as August 16 when he claimed – correctly, in retrospect – that the Congress will not field a Muslim candidate in the bypoll. By fronting himself as a candidate, the AIUDF chief, currently an MLA from central Assam’s Binnakandi seat and a former three-time MP from western Assam’s Dhubri, is going all in to reclaim the party’s core constituency. The arithmetic aligns: Nagaon has four Muslim-majority Assembly segments, Dhing, Rupahihat, Lahorighat and Samaguri, and four others – Nagaon-Batadraba, Jagiroad, Morigaon and Raha; over 55% of the parliamentary constituency’s voters are minorities.

The BJP and AIUDF, with their respective Nagaon picks, have boxed the Congress in from both flanks. State BJP chief Dilip Saikia and the CM have acknowledged the odds in a ‘non-traditional’ seat. The BJP is betting on a non-Muslim consolidation for Mr. Devasish Sharma, the former Nagaon Deputy Commissioner whose transition from bureaucrat on September 3 to BJP politician five days later sparked Congress outrage. The strategy, the CM spelled out, is to maximise its advantage in the four non-minority-heavy segments and narrow deficits in the rest.

Mr. Ajmal and Mr. Salam’s candidatures ensure that every Muslim vote would be equally fought for. A Congress victory could only come about if it manages to draw support across sections of voters – essentially making its old winning formula work. The party could not afford to alienate non-minority voters with a Muslim pick, having won the Lok Sabha seat twice in succession even as it slipped elsewhere against the BJP. The Nagaon poll is thus Congress’s to lose.

“Congress will secure victory once again in the Nagaon bypoll. Consider this as an announcement,” Mr. Gaurav Gogoi had said even before the party announced its choice.

A win here would indeed signal a vital shift: a diverse electorate, bridging religious divides, voting the Congress candidate first past the post and giving the party a credible shot at taking on the BJP five years down the road. A failure would mean the fundamental factor underlying its Assembly election rout persists – an inability to appeal to the Assamese Hindu voters beyond a certain threshold.