Ed Miliband is to launch Labour's campaign for council elections in England, saying the party will be the "first line of defence" against cuts.
The Labour leader will argue that local authority budget cuts will hit the poorest communities hardest and his party will stand up for those affected.
David Cameron told Conservative MPs on Wednesday they could win the "big argument" over the extent and speed of coalition plans to cut the deficit.
Voters go to the polls on 5 May.
More than 9,500 council seats will be contested in 279 local authorities across England, on the same day as devolved elections in Scotland, Wales and Northern Ireland and a referendum on the future of the UK electoral system.
Although Labour has won both by-elections held since Mr Miliband became leader in September, next month's polls will be the first across-the-board national test of his performance.
In his speech later, he will argue that reductions in councils' spending power this year will be equivalent to a £182 cut for every two-parent household with children.
"Cuts designed by David Cameron and Nick Clegg are coming direct from Downing Street to your street," Mr Miliband is expected to say.
But he told BBC Radio 4's Today programme he was "proud" of Labour councils' record on making efficiency savings in "difficult" circumstances - and rejected coalition claims that some were deliberately cutting services to embarrass the government.
"It's nonsense for the prime minister to somehow say that Labour councils are making politically-motivated cuts to services.
"They are making efficiency savings and they are doing their very best to protect services that people really value and contribute to social justice in this country."
Under plans announced in October, central government funding for local authorities will fall by 28% over the next four years.
Ministers say councils can cut back on bureaucracy and procurement costs to mitigate the impact on core services used by the public and stress they are providing transitional funding for the first two years for the most affected councils.
Labour, who say this funding will provide only a "small cushion" for a short while, argue that councils are being forced to "frontload" cuts to services into the first two years. And they say town halls in more deprived parts of the country are being unfairly treated.
'Hold its nerve'
"Areas with the greatest need are being asked to bear the greatest burden," Mr Miliband is expected to add.
"The worst-off areas are being hit the hardest while the average family will be hit much harder than people in David Cameron's constituency.
"Labour will be your community's first line of defence against the damage being done by a Conservative-led government and their Liberal Democrat allies."
He will add: "Labour launches our election campaign with a clear pledge to people across the country: we will be your voice in tough times."
The government has accused Labour of having no concrete plan to deal with the UK's record peacetime deficit while stressing steps it is taking to help people with rising living costs - such as ensuring no council tax payer in England will see a rise in their bills this year.
Addressing a meeting of Tory MPs on Wednesday evening, Mr Cameron said they should be confident that they could win the key economic argument about the deficit and the pace of cuts.
The prime minister pledged to spend three days a week campaigning ahead of May's poll and urged MPs to campaign "hard locally".
Lib Dem leader Nick Clegg has urged his party to "hold its nerve" ahead of the elections, saying they are taking difficult decisions in the national interest and will be rewarded in the long term.
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