Ed Miliband will launch an attack on David Cameron today for "betraying" ordinary people to please his millionaire Tory paymasters.
The Labour leader is to link the cash-for-access row with the axing of the 50p tax rate and controversial NHS shake-up to portray the Prime Minister as "desperately out of touch".
Mr Miliband will also seek to re-establish his party's economic credentials by promising "different values" rather than extra spending.
Unveiling a "pledge card" of policies to protect family budgets, he will tell an audience in the Midlands: "The last week has shown this Government for what it is: one that works for the millionaires - but not for squeezed middle families who work so hard to make ends meet, not for pensioners who have worked hard all their lives, and not for young people who can only dream of working at all."
Mr Miliband will condemn the Government's so-called "granny tax", cuts to working tax credit, and the reduction in the top rate of income tax for earnings above £150,000.
He will also accuse Mr Cameron and the Liberal Democrats of pushing through changes to the health service that would do "huge damage" and cost billions of pounds.
"David Cameron once promised to be a different kind of Tory. He said he cared about the NHS and about people struggling to get by. He said the Conservatives were no longer the party of the wealthy few. But he has betrayed that promise," he is to say.
"From the Budget to the NHS, David Cameron's Tory-led Government has revealed its true colours. He is desperately out of touch with the vast majority of people in this country. He has closed the door on the squeezed middle."
Referring to the cash-for-access allegations that forced the resignation of Tory co-treasurer Peter Cruddas, Mr Miliband will go on: "David Cameron prefers to listen to those who have given millions of pounds to the Conservatives Party in exchange for donor dinners and special access in Downing Street."
Mr Miliband will insist that Labour did "great things" when it was in power. But he will also admit that people felt that the party had "lost touch" by the end of its term.
"I know what you know: that we live in a time when there is less money around. That is true for you and your family. And it's true for governments," he is to say.
"So today I am setting out some simple, affordable and practical measures which will help squeezed middle families in these tough times.
"This five-point action plan, alongside our plan for growth and jobs, addresses the fundamentals of life: the cost of heating a home or getting to work, paying the grocery bill and ensuring your family is not ripped off.
"The Conservative Party will have you believe that it's impossible to help the squeezed middle when times are tough. Our family budget action plan shows it's possible to make a real difference for pensioners, for hard-working families, for young people, even when there is less money around.
"These are measures that do not require extra spending. But they do require a different set of priorities, different values, a government that is on your side, and sometimes the courage to take on powerful and well-financed organisations which will not like it."
The card, headlined "with you in tough times", says that Labour will "end rail rip-offs by capping fares increases on every route".
It also commits the party to "force the energy firms to cut gas and electricity bills for four million over-75s" and "stop excessive fees charged by banks and low cost airlines".
Yesterday Mr Miliband promised to publish details of his private meetings with major Labour donors as he renewed his call for an independent inquiry into allegations that Tory supporters were offered access to the Prime Minister in return for cash.
He is expected to release a list by the end of this week.