David Cameron will seek to reaffirm his "compassionate Conservative" credentials on Wednesday when he gives his keynote speech to the Conservative Party conference in Birmingham.
Faced with a surly parliamentary party increasingly unhappy with life in coalition with the Lib Dems and a Labour Party buoyed by Ed Miliband's speech to his own conference last week, the prime minister will seek to remind Tory activists why they voted for his plan to modernise the party in the first place.
Cameron will also warn that Britain faces a stark choice in turbulent economic times: "Sink or swim. Do or decline."
In his speech Miliband sought to appropriate the centrist Conservative tradition of One Nation politics, an attempt to claim the centre ground that Cameron will seek to repel.
"My mission from the day I became leader was, yes, to show the Conservative Party is for everyone: North or South, black or white, straight or gay," he will say.
"But above all to show that Conservative methods are not just the way we grow a strong economy, but the way we build a big society.
"That Conservative methods are not just good for the strong and the successful but the best way to help the poor and the weak and the vulnerable.
He will add: "Because it's not enough to know our ideas are right. We've got to explain why they are compassionate too."
Over the last six months the government has been battered by allegations that it is both incompetent and only out to look after the interests of the rich.
On Tuesday night Cameron's former press secretary warned the prime minister that the perception that the party did not care about the vulnerable and was run by a wealthy elite was a "major problem".
In Manchester last week Ed Miliband solidified his position as Labour leader by delivering, without notes, a highly personal speech that drew on his background and comprehensive education to explain his political views.
Today Cameron will also seek to present voters with his own background in an attempt to counter the view that he is simply a "posh boy" who does not understand the average person's life.
He will reveal how his father, Ian Cameron, helped support his own mother when she was deserted by her husband and that his father's commitment to providing for his family despite his disability meant his life was "not a hard luck story, but a hard work story".
"There is nothing complicated about me. I believe in working hard, caring for my family and serving my country," he will say.
"And there is nothing complicated about what we need today. This is still the greatest country on Earth... but it's tough. These are difficult times. We are being tested.
"How will we come through it? Again it's not complicated. Hard work. Strong families. Taking responsibility. Serving others."
The prime minister will warn that the decisions taken in the next few years will have profound consequences for Britain's economic prosperity as well as its position in the world.
"Unless we act, unless we take difficult, painful decisions, unless we show determination and imagination, Britain may not be in the future what it has been in the past," Mr Cameron will say.
"Because the truth is this: We are in a global race today and that means an hour of reckoning for countries like ours."Suggest a correction