If he had wanted to, Sonowal could have made great political capital out of this. He is, after all, only carrying out an order by the Supreme Court. He could have argued that the task of weeding out Indians from non-Indians is not something he would have done.
But this would be inaccurate. Sonowal cut his teeth on precisely this kind of identity politics when he joined politics and became president of the All Assam Students Union (AASU) in 1992, a post he continued to hold until 1999. He then took the next logical step of joining the Asom Gana Parishad (AGP) in 2001 and was elected as a Member of the Legislative Assembly the same year.
AASU and AGP were based on the "sons of the soil" model. Sonowal refined this by expanding and developing the Assamese identity to include tribal student groups so that Assam would be Ahom -- where the domination of the indigenous would prevail. The thrust was to counter the Congress argument -- that so long as the "Ali" (Muslims), "Kuli" (tea estate workers) and "Bangali" (Bengali Hindus, usually clerks and petty trader who came to Assam when Bangladesh was carved out) were with the Congress, the party could never lose Assam.
But the AGP was a sinking ship and as the leadership divided and sub-divided, Sonowal chose the only option available to a professional politician: He joined the Bharatiya Janata Party (BJP) in 2011. Many party colleagues followed him into that party. He was appointed the president of the Assam unit of the BJP in 2012, which is a pretty rapid promotion. After all, despite years of work by the Rashtriya Swayamsevak Sangh (RSS), the BJP had no real place in Assam. In that sense, he was a product, not of the Atal Behari Vajpayee-LK Advani BJP, but of the Narendra Modi-Amit Shah BJP.
The rest of the story is well known. Sonowal challenged the Illegal Migrants (Determination by Tribunals) Act, which provided special protections against undue harassment to "minorities" affected by the Assam agitation, and made it difficult to deport illegal immigrants. This was primarily because the Act put the onus of determining the person's nationality on the accuser rather than on the accused, a departure from the Foreigners Act, which applied to the rest of India. In 2005, the Supreme Court struck down the Illegal Migrants Act as unconstitutional.
Sonowal continued to be Assam BJP chief until his return to the Lok Sabha in the 2014 polls. He was made a Minister of State in the Narendra Modi government. He was appointed Assam unit chief again in 2015, a year ahead of the state polls. However, there was a slight setback. The BJP brass, in its wisdom, decided to import Himanta Biswa Sarma from the Congress into its party. Around the same time, Louis Berger, an American firm had admitted in a court in the United States that it had bribed officials and politicians across the world to win projects. It said it had bribed Indian officials in Goa and Assam for water development projects in 2010, when Sarma was the heading the relevant ministry in the state. Two politicians held a press conference -- Sonowal and Kiran Rijiju from Arunachal Pradesh, now a junior home minister. Efforts were also made to raise questions about the Saradha scandal, a West Bengal-based Ponzi scheme that collapsed in 2013, and Sarma's role in it (he was accused of accepting bribes from the Saradha founder).
But all this was of no avail eventually. The BJP's most influential general secretary, Ram Madhav, stood firm. Further, the leadership was unbending enough only to name, in January 2016, Sonowal as its chief ministerial candidate in the state, should the party manage to get the numbers to form a government. This was a departure from tradition. Elections followed and the party got 45 per cent of the vote and formed a government in coalition with Sonowal's former party AGP.
The rivalry between the two leaders, thankfully, has not had any ramifications on the cleavages and anxiety caused by the NRC. But it could if Sonowal begins to feel insecure or if the BJP decides to project an alternative to him. Cynical? Maybe. But, that's how politics works.