Senior federal minister Simon Crean warns that Labor's model of changing leaders after bad polls is "broken and discredited".

The former Labor leader was commenting on renewed speculation over the party's leadership, sparked by Monday's Nielsen poll which showed the ALP dropping four percentage points in the two-party preferred vote to 45 per cent.

The poll also showed support for former prime minister Kevin Rudd as preferred Labor leader was 61 per cent compared to 35 per cent for Prime Minister Julia Gillard.

But Mr Crean would not be drawn into the latest round of leadership speculation.

"I think that the Labor party model in changing leadership every time there's a bad poll is broken and discredited," he told reporters in Canberra on Tuesday.

"It happened when I was the leader (and) it's happened since.

"What you can't have is a belief in the revolving door of leadership as the salvation to your position in the public arena."

Mr Crean said he took Mr Rudd at his word that he wasn't interested in challenging for leadership.

He added that he firmly believed Labor could still win the September election.

"It is difficult - you'd have to say the focus of the polls show how difficult it is but it's doable," he said.

Asked whether Ms Gillard was finding it hard to get her message out, Mr Crean said: "I think it's very hard for the public to listen when the oxygen is deprived."