Work and Pensions Secretary Iain Duncan Smith has played down speculation of a rift with George Osborne over plans for fundamental welfare reform.
Mr Duncan Smith insisted he and the Chancellor were "very close" over whether money should be invested up-front in a new simpler system in order to reduce costs going forward.
He also stressed that he believed the changes - which aim to ensure people are always better off when they work - would deliver savings immediately as well as in the longer term.
The intervention came amid renewed rumours of tensions between the two Cabinet ministers, with the coalition's crucial comprehensive spending review little more than a month away.
Last month Mr Osborne and Mr Duncan Smith were reported to have had a blazing row over the multi-billion pound funding needed to achieve fundamental reform of the benefits system.
They were subsequently said to have struck a deal on the issue, but more signs of friction emerged last week after the Chancellor indicated that the Department for Work and Pensions had agreed to shave an extra £4 billion from the benefits bill.
Interviewed on Sky News' Jeff Randall Live programme this evening, Mr Duncan Smith said he "recognised" the need to make savings in order to fund the investment.
He said he had already agreed to cut £11 billion from welfare and there was "more to come". But he stressed those reductions were part of a "trade-off".
"There's not an endless pot, I recognise that," he said. "No-one is more committed to saving unnecessary spent money than me. There is lots of this money in these areas that we think is ill-advised, doesn't do the work it's meant to do. We can save that, we can use it.
"But there's something else too. The present system is so broken, so complicated that even today (HM Revenue & Customs) wastes billions of pounds in overpayments to people it can't get the money back from."