David Cameron has admitted he has not managed to keep his pledge to "end Punch and Judy politics" - blaming the nature of prime minister's questions.
"I will absolutely hold up my hand...this is a promise I haven't been able to deliver," the Tory leader said.
The "adversarial" nature of PMQs meant he had not been able to adopt the "quieter tone" he had hoped for.
He said when it was in the national interest" his MPs had voted with the government, such as to renew Trident.
Last week at prime minister's questions, Mr Cameron called Prime Minister Gordon Brown "a loser" over his handling of the abolition of the 10p tax rate and calls for compensation for those worst affected.
In an interview with BBC Radio 4's Today programme, Mr Cameron was asked about his promise, during his 2005 campaign to become Tory leader, to see an end to "Punch and Judy politics".
Mr Cameron said: "I will absolutely hold up my hand... and say you're quite right, this is a promise I have not been able to deliver - I 'fess up to you if you like."
The quieter tone I had hoped we might have been able to have, the better discussion of politics at prime minister's questions, doesn't work
He said in terms of "the real politics" - like schools policy and renewing Trident nuclear weapons - he had got his party to vote with the government rather than "playing politics".
"I think that is a proper approach and that is ending an element of Punch and Judy politics but I do accept that at PMQs I do accept that I take a robust approach. It is robust. I don't make any apology for that."
He said prime minister's question time was "an adversarial system" adding: "I think the House of Commons is designed that, if you don't do that, you lose out."
Mr Cameron said he had been "very angry last week" as people had found out that Mr Brown's last Budget as chancellor, in which he announced the abolition of the 10p rate and a cut in the basic rate of income tax, had been "a complete con".
"He wanted to pose as a tax-cutter, he wanted to get the politics right and in the process he was prepared to hit five million people," Mr Cameron said.
He told the programme: "I've accepted to you, that the quieter tone I had hoped we might have been able to have, the better discussion of politics at prime minister's questions, doesn't work."
But he added: "When it comes to the important decisions about how we vote on bills, how we behave about legislation, acting in the national interest I think you can look at my leadership of the Conservative Party and say I really have delivered that."
During the interview, which comes just days ahead of local elections in England and Wales, he said there were "some good things" the Labour government had done to reduce poverty - such as the minimum wage.
But he said, while Labour's approach to tackling poverty was to redistribute money through the tax and benefits system, he believed it was time to tackle the "root causes" of poverty - like worklessness, family breakdown, alcohol and drug addiction.
Mr Cameron said a Conservative government would save money on the welfare system through stricter rules for those who refused back to work training - and use it to "get rid of the couples penalty in the benefits system", and reward families, which he said would lift 300,000 children out of poverty.
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