More than a dozen Labour MPs have expressed support for unions opposing government plans to cut 40,000 jobs in the civil service.
The MPs have tabled an early day motion at Westminster opposing the cuts foreshadowed in the Budget.
They say back-up for the minimum wage, the new deal on jobs, tax collection and school inspections could be hit.
One MP, John MacDonnell, feared the cuts "will have a detrimental affect on the service the public expect".
In his 17 March Budget, Chancellor Gordon Brown pledged to squeeze out more cash for frontline public services without increasing borrowing through efficiency savings.
The Department of Work and Pensions and the Education Department will bear the brunt of the job cuts but all departments will have to cut their administrative costs by at least 5% by 2008.
Mr Brown also unveiled plans to relocate 20,000 civil servants from London to the regions, saving an estimated £2bn over 15 years.
'Naive'
The plans have anger the Public and Commercial Services Union, whose general secretary, Mark Serwotka, said: "The misplaced view that the people affected by these cuts are faceless bureaucrats is simply not the case.
"They are hard-working public servants fulfilling vital tasks on both the
frontline and the back line up and down the country.
"To think that the back line can be slashed with out any effect on delivery is naive."
The plans to cut were welcomed, however, by Isabella Moore, president of the British Chambers of Commerce, who said "this will reduce the burden through the tax system on business".