Anna Hazare described the government draft as "worthless and good fornothing".
If it gets the cabinet nod the bill will be passed in Parliament on Dec 21.
As the winter session ends Dec 22, the government may extend it for a day Dec 23 or may reconvene Parliament from Dec 27-29 post-Christmas holidays to pass the Lokpal bill.
Parliamentary affairs minister PK Bansal has informed the main opposition Bharatiya Janata Party (BJP) about the government's intention to extend the session.
Both parties have also issued whips to their members to be present in Parliament till Dec 22.
Sources said an extension might be required as the draft bill has over 60 amendments and more could come from opposition members when the legislation is debated in Parliament.
Sources said keeping in mind the high number of amendments, the government is likely to bring a new bill in the Lok Sabha for clarity after withdrawing the one already introduced.
The cabinet meeting could not be held Monday after home minister P Chidambaram found fault with the drafting of the bill.
A crack team including home minister P Chidambaram, law minister Salman Khurshid and minister of state in the Prime Minister's Office (PMO) V Narayanasamy - all lawyers by training - scrutinised the government draft for any loopholes in a meeting which lasted over two-and-half hours.
Khurshid later told reporters the final draft will be cleared by finance minister Pranab Mukherjee and Prime Minister Manmohan Singh on Monday night.
According to sources, the bill is likely to bring the Prime Minister under the ombudsman with riders. Sources said the government is not keen on bringing the Central Bureau of Investigation (CBI) completely under the Lokpal, as being demanded by Hazare.
In a first, the bill, which will suggest a constitutional status for Lokpal, will provide for reservation for SC/ST, women and minorities in the anti-graft ombudsman.
While the government is open to bring the 57 lakh lower bureaucracy under the Lokpal, with proper procedures, it is unlikely to bring a citizen's charter under it. The government plans to introduce a separate bill for the purpose, said sources.
Government sources said they hope the draft bill would be acceptable to a large number of people in the house except those who are opposed to the concept of Lokpal.
Minister of state for planning Ashwani Kumar said: "The government and Congress are trying to build consensus on the Lokpal by consulting its allies and parties in opposition."
However, sounding a word of caution, union minister Farooq Abdullah said Parliament should keep in mind that "a super government to the government is not formed while creating the Lokpal".
Meanwhile, in Pune Hazare termed the proposed bill as "worthless and good for nothing" and cancelled his plan to visit Delhi on Monday.
"We will fill up jails in New Year," said Hazare reiterating he would launch a new movement, 'Jail Bharo Andolan' (fill up jails), from Jan 1 in front of the houses of Member of Parliament (MPs) if they attempt to dilute the Lokpal bill.