But party insiders say the passage of the Bill in the Upper House has less to do with the numbers and more with inter-party chemistry, where the party's top guns, led by Amit Shah, come into the picture.
At least two BJP Ministers a Rajya Sabha member and the other an influential party General Secretary say the chemistry will pave the way for the CAB passage.
The Rajya Sabha has a total 245 members. But now, with a few vacant seats, the House strength comes down to 238. BJP needs 120 votes to pass the Bill, which is one above the halfway mark (119). The BJP has 83 MPs in the upper house and its National Democratic Alliance has 94 MPs.
Apart from BJP's 83 MPs, the NDA also has 6 MPs from the Janata Dal (United), 3 from the Shiromani Akali Dal and 1 each from Lok Jan Shakti Party and Republican Party of India. The entire count goes up to 94.
There are 12 nominated MPs in the Rajya Sabha. The BJP is confident of support from 11, which includes Subramanian Swamy, Swapan Dasgupta, Rakesh Sinha among others. The only nominated MP the BJP is not counting on is K.T.S. Tulsi, say sources.
With 11 more Rajya Sabha members on board, the NDA's count goes up to 105, where it still needs 15 MPs' support. Here comes the BJP's 'chemistry' to enable it to take the total tally to 120, making a smooth passage for the Citizenship Amendment Bill.
All India Anna Dravida Munnetra Kazhagam or AIADMK is seen as part of the NDA and in one viral video, Amit Shah was earlier heard advocating AIADMK Ministers to use NDA banner for events in Tamil Nadu rather than that of its own.
The alliance between the two parties in Tamil Nadu, however shaky, has been for all to see. Two senior Union Ministers are pressed to take the southern party on board. The BJP is confident the AIADMK's 11 MPs will vote in favour of CAB on Wednesday.
With 116 MPs, the BJP would need 4 more. But Amit Shah, who is personally overlooked the floor management in the Lok Sabha on Monday, doesn't want to leave anything to chance. Hence, the BJP wants to get a few extra votes in its kitty.
Sources say, Naveen Patnaik's Biju Janata Dal was approached long before the Parliament session started for its "help" on passing the Bill in the Upper House. "Not only Naveen Babu, but V. Karthikeyan Pandian was also approached for this purpose," said a source.
Pandian is the backroom person of the Odisha CM and considered de facto Chief Minister. The BJP has reason to believe that BJD's 7 MPs will vote in favour of the CAB.
With three extra votes than required, Amit Shah's party has also reached out to Jagan Mohan Reddy's YSRCP which has 2 Rajya Sabha members.
Though Shiv Sena has said it will oppose the Bill, many in BJP are hopeful that the Sena at best may end up walking out, which will eventually help the government.
"Wait and watch. We will be having the last laugh tomorrow", said a BJP General Secretary who is privy to talks with YSRCP. He said the government has more numbers than it needs for the Bill to pass the RS test.
The NDA government had introduced the Bill in its previous tenure and got the Lok Sabha's approval. However, CAB couldn't pass the Rajya Sabha test due to vehement protests.
With more protests mounting against the government this time, Home Minister Amit Shah is personally overseeing the arrangement to ensure the Bill sees the light of day.
(Anindya Banerjee can be contacted at anindya.b@.in)
( With inputs from IANS )