It will be a touch-and-go affair in the Upper House, remarked a senior Congress leader underlining that there were many ifs and buts for the bill to be passed.
The United Progressive Alliance does not have a majority in the 243-member Rajya Sabha, which has got two vacancies.
The leader said that if the government's bid to get the Bill passed in the Upper House fails, then a joint session would have to be convened before the Budget Session that generally starts in the second week of February.
The Congress has 71 members, while its allies the Dravida Munnetra Kazhagam has seven, the Trinamool Congress six, the Nationalist Congress Party seven, the National Conference two and the Rashtriya Lok Dal one. This comes to 94.
The party also enjoys the support of some one-member parties and some independents and others. The total number of independent and others is six, while nominated members are eight.
Two of the nominated, Mani Shankar Aiyar and Bhalchandra Mungekar, have already joined the Congress.
A Union minister, belonging to the Congress, expressed the hope that the government would be able to muster enough support for the passage of the crucial legislation through some parties abstaining from voting or staying away.
On the Opposition side, the Bharatiya Janata Party has 51, the Left parties have 19, the Janata Dal-United eight, the Biju Janata Dal six, the All India Anna DMK five, the Telugu Desam Party and Shiv Sena four each, the Akali Dal three and the Asom AGP two.
Some of the outside supporters of the Congress-led UPA like the Bahujan Samaj Party, which has 18 members, the Samajwadi Party with five members and the Rashtriya Janata Dal with four, had walked out in the Lok Sabha before the crucial vote on Tuesday night.
If they do a repeat act in the Upper House, the half-way mark gets reduced drastically from 122 to 109, which is unlikely to be a tall order if government managers work overtime to garner support of smaller parties and independents.
Some of the outside supporting parties like Lok Janshakti, Bodoland People's Front, Nagaland People's Front and Sikkim Democratic Front have one member each in the House.
Faced with the embarrassment in the Lok Sabha on Tuesday over the Constitution Amendment Bill on the Lokpal, government managers are leaving nothing to chance to ensure the presence of all members of the party as also its allies.
The last time a joint session had taken place was in 2004 to repeal the controversial Prevention of Terrorism Act.