Labour Party leader David Cunliffe says if he was Prime Minister he would hold his ministers to a higher standard than John Key does.
Mr Key is under pressure to fire Justice Minister Judith Collins, who gave the name of a public servant to blogger Cameron Slater.
The minister suspected the public servant, Simon Pleasants, had leaked information about Finance Minister Bill English double-dipping on his accommodation allowance. Mr Pleasants had not leaked any information, but was subject to abuse on Mr Slater's Whale Oil blogsite and also received death threats.
Opposition parties and the Public Service Association say Ms Collins should go but Mr Key is standing by her.
David Cunliffe told Radio New Zealand's Morning Report programme Ms Collins' behaviour was unbecoming of a minister, especially a Justice Minister who is meant to uphold and guide the formation of the law.
