The Liberal Democrat Chief Secretary to the Treasury said on a visit to Eastleigh: "I've got no plans to reopen the welfare issue. We agreed significant measures in the autumn and we're legislating for those at the moment. The balance has to be found from departmental budgets. Everyone's got to play their part."
At the moment, the Treasury is drawing up plans for the financial year 2015/16, which begins a month before the next General Election. Chancellor George Osborne is expected to announce the results of his review in June.
While hospitals, schools, overseas aid and the equipment side of the defence budget will be protected, all other departmental budgets face cuts. Mr Alexander's Cabinet colleagues are busy making their cases for the axe to fall elsewhere.
It is thought Theresa May, the Home Secretary, Philip Hammond, the Defence Secretary, and Chris Grayling, the Justice Secretary, are insistent any further cuts must come from Iain Duncan Smith, the Work and Pensions Secretary.
Given that the welfare budget, at £200bn, is the largest, there had been an expectation Mr Osborne might be looking to take off another slice for 2015/16. Mr Alexander has now made clear, from the LibDems' viewpoint at least, that benefits will also be protected.
"In the autumn statement, we made some difficult decisions on welfare. What remains is departmental spending. We've got no plans to go back to the welfare budget as part of that process. What I'm focused on is finding that £10bn or so from within the spending the Government departments do," he explained.
Earlier, the Highland MP warned colleagues against "fiscal nimbyism", adding: "Just because you take a strong position in favour of deficit reduction does not mean you can then protect your own spending."
One colleague Mr Alexander has taken aim at is believed to be his own LibDem colleague, Vince Cable, the Business Secretary, who has argued that borrowing should be allowed to rise further to fund capital investment projects.
However, the Chief Secretary is opposed to this, believing any additional public investment should come from departmental savings.
Earlier this week, the deputy Chancellor attended Mr Osborne's brain-storming session on the Budget at his country retreat of Dorneywood in Buckinghamshire. It is thought part of the exercise was to ensure the "omnishambles" of the last Budget is not repeated on March 20.
The Chief Secretary has made clear the LibDems' priority is to get as close to the £10,000 tax-free personal allowance as possible this spring; the Coalition's aim is to reach the target by the next election.