A candidate of the Bodoland People’s Front (BPF) on Thursday joined the ruling BJP ahead of the third phase of polls in Assam.

The Congress has decided to challenge the defection before the Election Commission while the BPF has decided to back an Independent candidate.

BPF’s Rangja Khungur Basumatary, a contractor who was contesting the third phase of polls from Tamulpur constituency in Baksa district on April 6, joined the BJP in presence of Union agriculture minister Narendra Singh Tomar and “appealed” to voters to support the United People’s Party Liberal (UPPL) candidate Leho Ram Bodo.

The UPPL is part of the BJP-led alliance in the Assembly polls, which is getting tighter by the day as both the Congress and BJP-led alliances are going all out to woo voters.

The Congress, which leads the Opposition 10-party grand alliance of which the BPF is a partner, described the “unprecedented” move as “cheating”.

BPF general secretary Prabin Boro told The Telegraph that the candidate had “sold himself” to the BJP and that they were planning to “back” an Independent instead of wasting time on a “betrayer”.

Reports about Basumatary switching allegiance to the BJP started doing the rounds since Wednesday evening. He ended all speculation by joining the saffron party while polling for the second phase was under way on Thursday.

In his fifties and one of the 11 candidates in the fray, Basumatary, told a section of the media that he had joined the BJP of his own volition after he did not receive support, including financial, from his BPF colleagues in his constituency.

He also said that he had reached out to cabinet minister and senior BJP leader Himanta Biswa Sarma and to former BPF legislator Emmanuel Mosahary before taking his decision. Sarma had tweeted about Basumatary’s impending defection on Wednesday night.

The BPF has fielded 12 candidates in the Bodoland Territorial Region. It had won all the 12 seats in 2016 as part of the BJP-led alliance but was dumped by the ruling party this time in favour of the UPPL.

An official in the office of the chief electoral officer said they are yet to receive any intimation or complaint about the development but were discussing what will be their course of action if they get a formal intimation from any quarter.

A former Election Commission official told this newspaper that the election in the constituency will be held as scheduled since the development took place after the date of withdrawal of nomination.

“It will all depend on what the BPF decides after the election. If he (Basumatary) wins, he may have to face the anti-defection law. There can also be legal recourse since there is an apparent breach of trust. It is a new experience for everyone — the poll officials or the parties. I have not heard about such a case before in the state,” he said.

Senior Congress leader Manish Tewari and PCC media department chairperson Bobbeeta Sharma attacked the BJP for Basumatary’s defection during a news conference in Guwahati earlier in the day, demanding that call records of Basumatary for the past seven days be made public and the deferment of polls in Tamulpur.

Vijay Gupta, a core committee member of the state BJP, said the development reflects the faith of the people, even those in the Opposition, in his party. “The development proves we are comfortably forming the next government in Assam,” he said.