The CPM and the CPI (ML) Liberation have put aside their ideological differences and come together for the first time in Bengal's electoral spectrum, adding a new dimension to the otherwise lacklustre campaign for the Naihati Assembly bypoll.

The Left Front-backed CPI (ML) candidate, Debajyoti Mazumdar, a retired bank employee and popular face among jute labourers, has been pitted against Sanat De of the Trinamul Congress and Rupak Mitra of the BJP in a constituency once considered to be a CPM stronghold.

The by-election at Naihati in North 24-Parganas, along with five other Assembly segments in Bengal, will be held on November 13.

The by-election was declared in Naihati after Trinamul’s sitting MLA Partha Bhowmik was elected to the Lok Sabha from Barrackpore.

While the BJP's campaign seems to have failed to make a mark, Trinamool thinks it can retain the seat by banking on De's popularity and the party's organisational strength. Left supporters hope the CPM-CPI (ML) alliance will consolidate voters opposed to the TMC and the BJP.

Naihati, several leaders of the CPM and the CPI (ML) feel, will mark the resurgence of Left forces in Bengal.

"Sitaram Yechury used to say that Left revival in the country cannot happen without rejuvenation of the Left forces in Bengal. Naihati is showing the way. All of us have to shun our narrow views and forge a bigger coalition of Left parties, groups and individuals in Bengal," CPM state secretary Mohd. Salim said while addressing a rally in support of Mazumdar in Naihati earlier this week.

CPI (ML) Liberation general secretary Dipankar Bhattacharya, who was on the dias alongside Salim, emphasised the need for a Left alliance to fight the "communal BJP" and the "corrupt TMC" in Bengal.

Justifying the alliance, Bhattacharya said: “It is the need of the hour since Trinamool’s tyranny and violence have crossed all limits. Stopping Mamata Banerjee’s autocracy is as important as opposing the BJP or Modi.”

The coming together of the two Left parties remains the high point of the contest in Naihati which the TMC had won by defeating the BJP's Phalguni Patra by over 18,000 votes in 2021.

The margin dropped to a little over 15,000 votes in Naihati, which is a part of the Barrackpore Lok Sabha seat, during the recent general election.

Despite victories in the Naihati Assembly segment in 2021 and the Barrackpore Lok Sabha constituency in 2024, the public outrage over the August 9 rape and murder of the junior doctor at RG Kar Medical College and Hospital and the coming together of the Left on a seat with a sizable presence of jute workers has made the Trinamool leadership exercise caution and put in extra effort in its campaign.

Refusing to give much importance to the alliance, Trinamool described the CPM leaving the seat for the CPI (ML) as a sign of the organisational weakness of the Left Front big brother.

Trinamool candidate and the party's Naihati town committee president Sanat De said: “The CPM has lost its base here and could not field a candidate. So they had no choice but to give the seat to the CPI (ML), which also has minimal presence in the area.”

In the 2021 Assembly elections, CPI (ML) informally supported the Left Front in 24 constituencies. But its “No Vote for BJP” campaign was viewed as passive support for Trinamul.

"The coming together of the two Left parties shows a change of circumstances," said a CPM leader who added that the RG Kar incident and people's movement catalysed the unity.

The leader said TMC supporters had attacked CPM and CPI (ML) activists who had recently taken part in an RG Kar protest rally.

“Trinamool, threatened by people’s support for the RG Kar movement, attacked the rally,” a CPI (ML) leader said.

While the alliance surprised many CPM grassroots supporters, party leaders emphasised the necessity of unifying the Left voters.

The CPM hopes to signal a new era of Left unity by backing Mazumdar's nomination. However, leaders of both the CPM and the CPI (ML) said the alliance did not mean slamming the door on the Congress, which fielded candidates for the six bypolls.

CPM’s North 24-Parganas district secretary Mrinal Chakraborty said: “The CPI (ML) has been working with us nationally. However, the unique political context in Bengal opened up this opportunity. When they expressed interest in becoming part of our political fight in Bengal, we welcomed it. Naihati will script a new chapter in Left unity in the state."

CPI (ML) Liberation politburo member Kartick Pal said: “Our alliance with the CPM nationally is longstanding. In Naihati, where we have an organisational presence in the jute belt, we believe Debajyoti Mazumdar’s reputation among labourers will resonate strongly. We are optimistic that Left voters will rally behind him.”

For the Naihati seat, the CPI (ML) has chosen a low-profile, grassroots-focused approach, prioritising door-to-door campaigning in the jute belt. On Saturday, Satyadeo Ram, who is the party's MLA from Siwan in Bihar, campaigned for Mazumdar in the labour colonies near Gouripur Jute Mill which has a concentration of Hindi-speaking voters.

Despite the Left thrust, Trinamul candidate De sounded confident about victory.

“Victory is assured. My concern is only the margin. Partha Bhowmik has pledged to increase it to 50,000 votes and we are determined to meet that goal,” De said.

The Naihati constituency includes 31 wards of Naihati municipality and a few panchayats.

On the other hand, BJP candidate Rupak Mitra said: “The decline in Trinamul’s support is evident. If this trend continues, it could signal the beginning of the end of Trinamul’s dominance.”