On the eve of the debate in Lok Sabha on Lokpal Bill, government on Monday struggled hard to muster support for the measure as the BJP and the Left stepped up heat insisting that they will press for amendments.

Claiming that all UPA allies "are on board", parliamentary affairs minister Pawan Kumar Bansal wanted other political parties not to press for any amendment to the "strong bill" which is a "fine piece of legislation" drafted after careful consideration and consultations with all concerned.

His refrain was that the process of law-making is not a static exercise and as one gathers experience one can make changes later. He noted that all political parties should realise that for the first time in 40 years, a bill on the Lokpal issue has reached considerations stage in Parliament.

Bansal brushed off speculation that Congress has issued a three-line whip asking all MPs top be present in the Lok Sabha on Tuesday as it was 'nervous". "Issuing whip is a legitimate exercise," he said.

BJP, however, made it clear that it will not relent on the changes sought by the party and it was up to the government to create a broad consensus by making amends wherever necessary.

"Congress has a nefarious design with the inclusion of an unconstitutional clause of relgion based reservation exceeding 50 per cent. It will make the bill infructuous in the eyes of the law", BJP spokesman Prakash Javadekar said.

A senior minister, who declined to be identified, said that the provision in the bill for reservation for minorities was "non-negotiable". He dismissed suggestions that Constitution has barred making any such provision.

Cranking up pressure,the CPI-M said it will move concrete amendments that includes creation of a separate investigation wing to further strengthen the measure which is "ineffective" in its present form.

"We are moving some concrete amendments which we think will further strengthen the Lokpal because the Bill, as it conceives of the Lokpal right now, .We are not very happy in the sense that it is not an effective Lokpal," Yechury told reporters.

The Left parties insist that they want to amend the present Bill on various counts, especially to provide for a separate investigating wing to probe corruption or inclusion of CBI's anti-corruption wing under the ombudsman's ambit.

The CPI(M) also wants inclusion of corporate crime in the jurisdiction of Lokpal, particularly those cases which cause a loss to the public exchequer and has the involvement of public servants.

Unhappy over content of the new Lokpal Bill, BJP said it would move amendments on issues like inclusion of CBI and against reservation for minorities.

Party sources said Leader of the Opposition in Rajya Sabha and eminent lawyer Arun Jaitley has been assigned the task of preparing the amendments.

BJP is likely to move six amendments to the new Lokpal Bill. The party is opposed to giving reservation to minorities in the nine-member Lokpal as well as the clause which states "not less than 50 per cent" reservation.

"BJP will move amendments on issues we do not agree with. We are custodians of a strong and effective Lokpal. Congress is not honest in its intentions and policies. It moves two steps ahead and four steps backward on the issue," party spokesperson Shahnawaz Hussain said.

Government, on its part, maintained that any "persistent objections" would mean that those resorting to it are opposing the bill.

Replying to questions, Bansal also conceded that the Congress and its allies alone would not be able to generate the support required for the passage of a Constitution amendment bill and other parties needed to be on board.