The Secretary of State for Education told the weekly meeting of the Parliamentary Labour Party: "Let's be clear - this is a Labour Bill which we should unite around. It is a Labour Bill which will drive up standards for all children, but particularly for those who need it most."
Her plea came as organisers of the revolt against the Education Bill predicted that 54 Labour MPs would vote against the measure and a further 25 would either oppose it or abstain. That would force the Prime Minister to rely on the support of the Tories to secure a second reading for the Bill.
Appealing for party unity, Ms Kelly said: "We should be making our case to the country and taking our case to the Tories. Let's force the Tories to vote against selection, to vote against interviewing, to vote for a stronger code on admissions and stronger powers for local authorities. Let's go through the lobby united as a party and proud to be doing our best for the nation's children."
She rejected the rebels' demand for her to drop the provision in the Bill that would give her a veto when local authorities want to open new comprehensives.
Her drive to sell plans for independently run "trust" schools was undermined when a former Downing Street adviser called for the proposal to be rethought.
Robert Hill, who was also a special adviser to Charles Clarke when he was education secretary, warned they ran the risk of a return to the grant-maintained schools of the previous Conservative government.
Mr Blair insists his reforms do not mean a return to the grant-maintained schools, under which schools were given incentives to opt out of council control. But Mr Hill, in a new book, argued the legislation should include a clause requiring the schools to collaborate with each other on issues such as admissions. "Many, many school leaders don't want to go back to a risk of the grant-maintained school arrangements where independence meant each school looked out for itself," he said.
The Government faces embarrassment tomorrow even though the Opposition's support will ensure the Bill secures a second reading. The Tories will vote against a government proposal to cut short the debate on the measure when it is discussed in detail during its later stages. If the Labour rebels join them, ministers could face a symbolic defeat and may have to grant more time for debate.
The Tories may oppose the measure at its third reading, a move which could scupper the Bill and force Mr Blair to resign. If ministers offer further concessions to the Labour critics during the Bill's passage, the Tories will reconsider their backing. "We are not giving the Government a blank cheque," a senior Tory source said yesterday.