Nick Clegg will insist today he did not enter Government "just to make cuts", in a sign that the Liberal Democrats reject David Cameron's call for a permanently smaller state.
The Prime Minister used his speech at the Lord Mayor's banquet to express his desire for a "smaller, leaner state... not just now, but permanently".
But a senior Liberal Democrat source said Mr Clegg's party would not support "cuts for cuts' sake" and it was "no secret" that the two coalition parties disagreed on the role of the state.
The latest sign of coalition divisions emerged as Mr Clegg prepared to launch an attack on Labour's economic policies.
The Deputy Prime Minister will argue that Ed Miliband's party would "wreck the recovery" if Labour governed alone after 2015.
In an effort to shift the debate away from Mr Miliband's high-profile pledge to freeze energy prices, Mr Clegg will say careful economic stewardship is the best way to protect household budgets.
In an event at a west London supermarket he will say there are "no quick fixes" to repairing the damage done by Labour, but all the Opposition could offer was an energy bill freeze which was "too good to be true".
Mr Clegg will say: " They honestly believe that they can walk back into Downing Street with a giveaway here, a gimmick there, but no credible economic strategy.
"Do you know why Ed Miliband suddenly wants to talk about the cost of living?
"Because they've lost the bigger economic argument. Where are the million lost jobs they predicted? Or the flatlining GDP? Where is the double-dip recession that never happened? Or - as David Blunkett warned - the post-Soviet meltdown?
"Plan A hasn't failed, it's working. And the truth is that healthy household budgets flow directly from a healthy economy. The two go hand in hand."
The Lib Dems' strategy for the 2015 election is to claim that they could offer social fairness in coalition with the Tories or economic credibility in a partnership with Labour.
Mr Clegg will say: " The Labour Party can carry on lecturing us all on fairness, but you cannot magically create a fairer society without bothering to build a stronger economy.
"A fairer society, where we ease the burden on struggling families, depends on a stronger economy, where we enable everyone to get on in life. The only route to higher living standards is shared prosperity and sustainable growth.
"So don't be fooled again: you cannot afford Labour. Let loose in government on their own they would wreck the recovery - costing jobs, driving up interest rates and undermining the growth needed to cut tax bills and fund public services.
"They cannot be allowed to undo all of the sacrifices that have been made and everything that has been achieved - the British people would pay the price."
Mr Clegg is expected to say "my party didn't come into government just to make cuts", and senior party sources stressed the difference between his view and the Conservative ideology.
A source said: "It's no secret that there's a disagreement between the Lib Dems and the Conservatives on the role of the state. We absolutely don't believe in cuts for cuts' sake.
"We are about getting the balance right between a credible economic policy that takes the tough decisions to clear up Labour's mess and balance the books while also investing in public services that we need.
"It's another example of where we disagree with the Conservatives on core economic policies."