The prime minister and his deputy reminded ministers that reducing the deficit is the “most urgent issue facing Britain”.
But the pair confirmed that any proposals to promote economic growth will be treated favourably in the departmental spending review.
The joint letter comes as government departments are negotiating with the treasury over the scale of the cuts with some areas like transport facing reductions of up to 40%.
The pair wrote: “Whatever the options on the table, whatever the decision to be made, the same questions must be asked: will it put more power in people’s hands? And will it equip Britain for long-term success?”
One contractor told the Enquirer: “The cuts are definitely coming but this could herald a subtle change in the message.
“I think the government is getting twitchy about being seen as purely a cuts machine so more emphasis is being put on long-term economic growth as well.
“A lot of that will be expected to be delivered by the private sector, but our hope is that more infrastructure investment will survive as part of a longer term growth strategy.”