Ministers were accused by the Tories of "panic" after they moved to delay until the early hours of today a vote on a crucial amendment opposing cuts in disability benefits.
Nearly 70 Labour MPs have signed the amendment, which would block plans to means-test and restrict entitlement to incapacity benefit, and government whips were keen to kill off the prospect of the largest rebellion since the general election.
However, the Conservatives warned they would force MPs to sit all night in the hope of triggering the potentially embarrassing vote around 8am today to coincide with morning radio news bulletins.
As disability campaignersdemonstrated outside the Commons, government business managers were indicating last night that such a Tory strategy may force them to put back the vote until next week.
The Prime Minister's official spokesman said earlier that Tony Blair was "absolutely determined" to see the reforms driven through and said they were "principled and right".
"This Bill has been put together with very great care and after extensive discussion and we believe it's fair and it's right. We were elected to reform the welfare state, and that's what we are doing," he said.
But even if the Government defeats the amendment, it faces even stronger opposition when the flagship Bill goes to the House of Lords, where the disabled Labour peer, Lord Ashley, is committed to lead the campaign against it.
Opening debate on the report stage of the Welfare Reform and Pensions Bill, Hugh Bayley, Social Security minister, said at least 14,000 mothers who earn at least pounds 30 a week would benefit from the changes.
Mr Bayley sought to avert backbench criticism of the legislation by stressing it would be complemented by other measures such as the Employment Relations Bill and the flagship working families tax credit.
He introduced the first of 86 government amendments, which improve maternity allowance, change work-focused interviews for all claimants and modify pension sharing arrangements.
But Jaqui Lait, Tory MP for Beckenham, accused the Government of introducing six new clauses to the Bill after "panicking" over the prospect of the rebellion.
"I am not naturally a person who believes in conspirations but I cannot help but wonder why this was announced now," she said.
"It seems to me that the aim was to ensure that the votes on disabled benefits would taken in the dead of the night." Ministers, she added, were "trying desperately to hold off a debate and vote on benefits" in another "abuse" of Parliament.
The overhaul of maternity allowances was still due to be reviewed and the changes would not come into effect for another 18 months, she added.
Iain Duncan Smith, the Tory Social Security spokesman, dismissed the maternity allowance change as a government attempt to buy off the rebels.
Such an important change should not have been introduced without giving Parliament a chance to consider it properly, he protested.
"This is a sop to your backbenchers to try to buy them off - what a joke," he told ministers. However, the move was passed by 365 votes to 130, a government majority 235.
Frank Field, MP for Birkenhead and one of the leading Labour rebels, warned ministers that the Bill's emphasis on means-testing undermined the capacity of thousands of people to put money aside to provide for themselves.
Mr Field has repeatedly warned that the proposals run counter to the Prime Minister's desire to abolish the "something for nothing" culture that had dominated the welfare state in recent years.
Although most of the controversy has centred on incapacity benefits, the former welfare minister last night offered an alternative source of dissent by tabling an amendment challenging plans to overhaul widows' benefits.
The Government wants men to be allowed to claim for the first time, but it aims to replace the retirement benefit with a six-month allowance.
Mr Field's amendment proposes that anyone aged at least 35 will be entitled to full widows' and widowers' retirement benefit and can have their State Earnings Related Pension taken into account for their claim.
Fears of a defeat on the Bill led the Government last week to cancel all leave for its MPs to ensure that enough loyal backbenchers would turn out.Reuse content