Nick Clegg has attempted to calm Liberal Democrat fears of a hammering in next month's local elections - urging activists to "take the fight" to their Tory coalition partners.
Only his party would protect Sure Start centres and libraries from spending cuts, he vowed, as the parties began campaigning in earnest ahead of the May 5 polls.
The elections have heightened tensions over the Westminster power-sharing deal, with one senior Lib Dem councillor calling for the party to pull out or risk a bloodbath at the ballot box.
There has also been public dissent at Cabinet level, with grassroots favourite Vince Cable attacking David Cameron over a speech on immigration.
And Labour leader Ed Miliband aimed to exploit those tensions when he took to the campaign trail - accusing the Lib Dems of being "locked in the boot" of the Tory-led administration.
Mr Clegg, the Deputy Prime Minister, began a day of campaigning in Sheffield - the city he represents as an MP and in which his party faces a battle with Labour to retain control.
He concentrated his attacks on Labour - accusing the party of putting politics before people by slashing local authority jobs and services - but he also turned his fire on Conservative-run councils, insisting the Lib Dems are the only party committed to protecting all libraries and Sure Start centres from cuts.
"Working together in the national interest does not mean we agree on everything," he said. "And it doesn't mean we shouldn't be taking the fight to the Tories in the local elections, criticising mistakes and wrong priorities wherever they occur."
Mr Miliband took the Labour fight to Newcastle - a key city he hopes to wrest from Lib Dem control - where he launched a vociferous assault on Mr Clegg's record.
He said the Lib Dems "have broken their promises" made one year ago when Mr Clegg gained a huge poll boost from the first of the general election televised debate.