How cynical was that? Shorten asked

Bill Shorten is refusing to concede Labor has cynically used out-of-context remarks by Malcolm Turnbull to question the prime minister's credibility.

The opposition leader claimed Mr Turnbull had been caught out when he said: "What political parties say they will support and oppose at one time is not necessarily what they will do".

But Mr Shorten overlooked a related passage, that linked it to Labor's opposition to coalition budget measures including the school kids' bonus - a position it junked during the campaign.

How cynical was that, he was asked by ABC Radio National's Fran Kelly on Wednesday.

"He said parties. He wasn't saying that is just about the Labor Party," Mr Shorten replied.

The fact Mr Turnbull was talking about his political philosophy that political parties can change their mind and don't have to keep their word in the lead-up to an election was what bred cynicism, he said.

Labor rushed out broadcast ads, partially quoting the prime minister, after Mr Shorten made the claim during an address to the National Press Club in Canberra on Tuesday.