Gam secured 67,242 votes against Basumatary's 25,101 while the third candidate, Bhaity Richong of the Socialist Unity Centre of India-Communist, got 2,265 votes.
Sarma also claimed that marriages of minors were registered by the Kazis earlier, but the proposed bill will prohibit any such move.
So far, over 30 people have died across Northeastern states due to heavy rainfalls, floods and landslides, according to media reports.
As results pour in for the four states -- West Bengal, Tamil Nadu, Kerala and Assam -- and one Union Territory -- Puducherry - here's a glimpse at the leaders who are trailing and those who are leading.
The Bharatiya Janata Party and its two Assam allies -- the Asom Gana Parishad and the United People's Party Liberal -- on Wednesday 'almost finalised' their seat-sharing pact for the Assam assembly polls and a formal announcement will be made in a day or two, sources said.
Assembly elections in Assam used to be a quiet affair and people outside the state would take little interest in the outcome. This time, even in faraway Delhi, people are keeping tabs on political developments in Assam.
Counting of votes is underway for four Lok Sabha and eight assembly Constituencies, spread across six states and one Union Territory where by-elections were held on Saturday.
81 per cent voter turnout recorded in West Bengal, 80 per cent in Assam.
Party general secretary Arun Singh told a press conference that Chief Minister Sarbananda Sonowal will contest from Majuli and minister Himanta Biswa Sarma from Jalukbari, constituencies these two top BJP state leaders currently represent in the 126-member assembly.
The BJP-led alliance in Assam is all set to form the government for the second successive term winning 72 of the 102 seats declared so far and is leading in three others.
The total worth of Assam Chief Minister Sarbananda Sonowal's assets, both movable and immovable, have increased by over 71 per cent since the last assembly polls in 2016, despite not having bought any new immovable assets.
Over 95 lakh voters will decide the fate of 539 candidates, including 43 females, in 65 constituencies spread across the state.
Those who have studied Assam elections say the high turnout has the Congress worried.
With two cabinet ministers and three ministers of state, the Northeastern region was on Wednesday handsomely rewarded by Prime Minister Narendra Modi in the first reshuffle of his ministry in the second tenure.
By-elections to Lok Sabha and assembly seats in the states of Assam, Tripura, Madhya Pradesh, Arunachal Pradesh, Tamil and West Bengal passed off peacefully on Saturday amidst tight security.
Even before the trends started coming, eager party workers were seen glued to their smart phones viewing the counting progress online.
Sonowal's name as the party's face came as no surprise as he came with a clean image and no baggage and enjoyed the confidence of Prime Minister Narendra Modi.
Labelling All India United Democratic Front chief Badruddin Ajmal as the 'enemy of Assam', state minister Himanta Biswa Sarma on Sunday asserted that he is an extremist in protecting Indian and the Assamese culture.