Nick Clegg will tell Liberal Democrat activists to "take the fight" to the Conservatives in the battle for next month's council elections in England.
Campaigning in Sheffield today, he will say that the Liberal Democrats should attack the record of Tory-run authorities when they have implemented spending cuts such as closing libraries and children's centres. He will claim that no Liberal Democrat-controlled council had shut a library or Sure Start centre, even though Labour and Tory authorities had done so.
The Deputy Prime Minister's remarks will be seen as another attempt to put light between the two Coalition parties ahead of the 5 May elections, when they will go head-to-head in many parts of the south, where Labour is weak
"We are making difficult decisions with compassion and intelligence, keeping pain to a minimum and protecting the people who need the most help," he will say. "Working together in the national interest does not mean we agree on everything," he will say. "When the Conservatives are making local decisions that we wouldn't make, we should say so. When the Conservatives are making mistakes locally, we should say so."
Mr Clegg's strongest criticism will be thrown at Labour. He will accuse Labour-run authorities of cutting services to put politics before people, responsibility and reality.
Ed Miliband will return Mr Clegg's fire in a speech in Newcastle today, accusing him of betraying people who thought they were voting for a progressive party at last year's general election.
He will say: "The truth is that the Liberal Democrats are not front-seat passengers or back-seat passengers in this government. They are locked in the boot of a vehicle which is travelling rapidly in the wrong direction."