George Osborne has been attacked for "hacking at the same people" by cabinet colleagues after proposing to cut £12 billion more from the welfare budget.
The Chancellor unveiled a further raft of welfare cuts on Monday as part of a £25 billion extra package of spending cuts that he argued were needed to eliminate the deficit by 2018.
However, cabinet colleagues, including allies close to work and pensions secretary Iain Duncan Smith, have hit out at the Chancellor's proposed cuts.
One source close to Duncan Smith told the Times that cutting benefit payments while refusing to touch benefits for pensioners was "unbalanced".
"You can’t keep hacking at the same people," the figure said.
Another Tory Cabinet minister doubted whether the Tories would draw enough political benefit from Cameron's "very expensive" pledge to keep the triple lock on pensions.
The Tory infighting comes after Nick Clegg branded it a "mistake" to hit the "working-age poor" and impose "cuts for cuts' sake".
Osborne insisted that "substantial savings" were needed in the welfare budget, adding: “That’s how to reduce the deficit without even faster cuts to government departments, or big tax rises on people."
“If you don’t make the welfare savings, you are going to have to find much bigger cuts in services and government departments. I would like to know where those cuts would come from."
Prime Minister David Cameron confirmed at the weekend that pensions would continue to rise by at least 2.5% and in line with wages and earnings until 2020 if the Tories won the next election.