John Key says the Government has done as much as possible for the poor after the mother of a family he championed said he was a political "arsehole".

In Opposition in 2007, the Prime Minister singled out McGehan Close, Mt Albert, as typical of the "growing underclass" that would be a priority for National.

He visited the Nathan family and invited Joan Nathan's 12-year-old daughter, Aroha, to Waitangi.

But now Mrs Nathan says although she still likes Mr Key personally, as a politician he is an "arsehole" and has done little to help the poor.

"He's just making everything better for high earners and not the low-income ones," she told Campbell Live.

Mrs Nathan, who recently had her sixth child, said her life was no better under Mr Key's Government.

"Bread, milk, everything that we need that is a basic necessity for us is going to be more expensive. It's going to be harder for us to feed our kids."

She was still on a domestic purposes benefit, though she did some work for National MP Jackie Blue.

Mr Key said the Government had a broad approach to help those on low incomes, including lifting the minimum wage from $12 an hour to $13 an hour, across-the-board tax cuts and the 90-day trial period for new workers that has reportedly created more jobs.

"No one's arguing that it's not tough for low-income New Zealanders. It actually has been pretty tough for them for a very long period of time. Decades, I might argue," Mr Key said.

In the context of the global financial crisis, the Government was making good progress, he said.

"We've done as good a job as we can in the conditions we've got to try and help low-income New Zealanders."

He said many houses in McGehan Close had benefited from the Government's home-insulation programme.

"It's a long process, lifting the opportunities for New Zealanders on low incomes. No one is arguing that."

Mrs Nathan, who no longer lives in McGehan Close, also said Aroha, now 16, had got caught up in the wrong crowd and was expelled from Mt Albert Grammar School last year. She was now in Child, Youth and Family care, which Mrs Nathan said was better because "it's a life I can't give her".

Mr Key has said he is sad Aroha is with CYF. He could not comment further for privacy reasons.