Mr Cameron is expected to speak about fairness in his conference address David Cameron will use his first conference speech as prime minister to warn that spending cuts will “not be easy”.
He will tell the Conservative Party faithful in Birmingham that jobs will be lost and programmes cut.
But he will also give his backing to wealth creators and pledge protection for the vulnerable, sick and elderly.
Ahead of the speech he apologised for not including changes to child benefit in his election manifesto.
Speaking to ITV News political editor Tom Bradby, Mr Cameron said the party had made clear during the election campaign that there were going to be “difficult cuts”.
He said: “We did not outline all of those cuts, we did not know exactly the situation we were going to inherit. But, yes, I acknowledge, this was not in our manifesto.”
When questioned, he said: “Of course I’m sorry about that but I think we need to be clear about why we’re doing what we’re doing.”
In his speech, Mr Cameron will try to defuse the situation by stressing plans for a tax break for married couples.
The government has denied plans for the tax break by 2015 has been announced in response to the backlash over proposals to end child benefit for high rate tax payers in 2013.
“Fairness means supporting people out of poverty, not trapping them in dependency”
Prime Minister David Cameron
Mr Cameron is expected to acknowledge the row in his speech, as a sign of how difficult reducing the deficit will be.
He will warn that jobs will be lost and programmes cut following the government’s long-awaited spending review on 20 October.
He will vow to protect the vulnerable – but he will also call for a debate on what fairness means in the new age of austerity, saying it should not just be about how much money is spent of welfare.
“You can’t measure fairness just by how much money we spend on welfare – as though the poor are products with a price tag; the more we spend on them the more we value them.
“Fairness means supporting people out of poverty, not trapping them in dependency.
Recognise marriage
“So we will make a bold choice. For too long, we have measured success in tackling poverty by the size of the cheque we give people. We say: let’s measure our success by the chance we give.”