TONY Abbott says he now has the "authority" to keep election promises.

He admitted he had broken them in the past but said it was not his fault.

The Liberal leader wants to make the September 14 election a referendum on trust and set out 18 promises ranging from abolishing the carbon tax to building the East-West Link tunnel.

He said they were commitments "you can trust me to keep".

When he was health minister in the Howard government he gave an iron-clad pledge on Medicare Safety Net thresholds before the 2004 election that was broken after the poll and cost families hundreds of dollars.

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Reminded of this by the Herald Sun, Mr Abbott said: "The truth is I was rolled by my senior colleagues.

"Then I was a man under authority. Now, if I can put it crudely, I am the authority."

He said Julia Gillard had fibbed her way into office by promising no carbon tax and a Budget surplus.

Mr Abbott told the National Press Club he would release his full costings between the May 14 Budget and polling day.

He admitted it would not be easy to cut taxes, pay off debt, have a surplus and increase spending.

"But we won't shirk the hard decisions, such as being upfront with people that the school kids bonus will go because it's a cash splash with borrowed money that has nothing to do with education," he said.

Families Minister Jenny Macklin said that would leave a typical eligible family with two kids $15,000 worse off over the course of their children's schooling.

Mr Abbott was embarrassed by the leak of emails between him, his wife Margie and his staff about yesterday's speech, which showed he wanted to convince people he was a "good bloke".

Mr Abbott said he could "live with the fact that not everyone likes me".

Mr Abbott said the 16 members of his front bench who were ministers in the Howard government, including Bronwyn Bishop, could expect to be ministers again if he won the election.

Originally published as You can trust me, says Abbott