The Conservatives’ former coalition partners are set to vote against George Osborne’s welfare cuts because of their impact on poverty.

The Liberal Democrats have tabled a parliamentary motion calling for the withdrawal of the Welfare Reform and Work Bill.

“It fails to balance economic prudence with the need to protect the most vulnerable in society,” the motion reads, particularly singling out cuts to disability benefits.

The motion is signed by all eight Liberal Democrat MPs, including former party leader and deputy prime minister Nick Clegg.

The Liberal Democrats’ opposition to the cuts comes as Labour is split on whether to support some measures in the Welfare Reform and Work Bill, which MPs will vote on Monday night.

Acting leader Harriet Harman and Blairite leadership candidate Liz Kendall have suggested that Labour should not necessarily oppose many of the cuts, including to tax credits.

“If we carry on making the same arguments as we have over the last five years we’ll get the same results,” Ms Kendall said last week.

While Labour is against the Government’s package as a whole, a motion proposed by the party’s interim leadership expresses support for a number of specific welfare cuts included in it, including the benefit cap and cuts to mortgage support.

Labour singles out disability benefit cuts as a negative part of the package, as well as the repeal of child poverty targets. It does not mention cuts to child tax credits in the text of its motions.

The benefit cap changes, supported by the Labour leadership, will push 40,000 more children into poverty, according to a leaked memo from the Department for Work and Pensions.

But a rebel group of Labour MPs have tabled an alternative motion to the party’s leadership which emphatically rejects the Government’s changes on the basis of their effect on child poverty and work incentives.

The SNP have also tabled their own motion which is emphatically against the package.