If Julia Gillard and the Labor Party lose Saturday's federal election, it will be because they failed to adequately answer one fundamental question - why, if the Government is any good, did you execute Kevin Rudd?

In the final week of a campaign dominated by the "Rudd factor" - with almost five weeks to refine a response - the best the Prime Minister could do at Wednesday night's Brisbane forum was this: "I was vice-captain of the team, I take my share warts and all.

"I stepped up when I, and overwhelmingly my colleagues, came to the conclusion that the best way of the Government being in the best shape to deal with the issues that the nation faced was for me to step into this position."

Convincing?

Granted, it is a question that neither Gillard nor her ministerial colleagues can answer totally candidly.

She can hardly say what really motivated 75 per cent of Labor MPs to throw out Rudd at the first opportunity. Of course it was appalling opinion polling, especially in his home state of Queensland. But it was much more than that. It was his autocratic style, his tendency to either abuse or ignore elected Members of Parliament. It was his history of over-promising and under-achieving; and providing his opponents with overblown rhetoric that would have haunted him in advertising through an election campaign.

No senior figure in the Labor Party can enthusiastically argue any of that. To do so would aggravate Kevin Rudd and his supporters and almost certainly lead to more leaks like those that almost ruined week two and three of the campaign.

But having said that, surely there was more to say to counter the accusations that came thick and fast from the public and the Coalition in equal number.

Leadership changes are routine in opposition and hardly unique in government. We didn't hear that. Tony Abbott challenged Malcolm Turnbull for the leadership because he did not share Abbott's scepticism on climate change. We didn't hear any of that. Abbott beat Turnbull by just one vote. When the Labor leadership was decided, Gillard had the numbers so decisively that a formal vote was not necessary. Yet the Government allowed Gillard's leadership to be presented as illegitimate while Abbott's was not. Why, when the Liberal leadership showdown was hardly ancient history, having happened just nine months ago?

Clearly, the public makes different judgments about prime minister's being replaced mid-term as opposed to opposition leaders. But Australia doesn't have a presidential system where people vote effectively for an individual. In Australia, the public votes for a party in 150 separate House of Representatives seats. Who leads that party is in the hands of the party itself. That's what sets Australia apart from the United States, and given the oft-repeated concerns that Australia has become too presidential, then maybe that too was a point worth making by somebody, somewhere.

Perhaps Labor strategists felt that to be too aggressive in its responses would simply feed the beast. But the beast has finished the campaign well and truly fed anyway.

It is hard to recall a time when a major party lost at least 5 per cent of the primary vote mid campaign. But that's what happened when the leaks brought all the attention on to the Rudd factor. Labor started in a winning position, fell well behind, and then by the final week got itself back in front again, but only just, and even then maybe not where it most needs support.

By the last week, interviewers everywhere, and the public too for that matter on talkback and at forums, were honing their questions to the key issues that had emerged through the campaign. By that process alone, the Rudd factor was back, bobbing up on the 7.30 Report, on Four Corners, and at the public forums. It hadn't gone away entirely in the madness of week two and three. In the last week, however, it didn't have quite the same nastiness to it; the sense that something was indeed very smelly within the bowels of the party itself. By day's end, it had more of an academic feel to it.

So as election day draws near, Labor will rue strategic errors like tossing in a peoples' assembly as a response to a serious policy vacuum on climate change. They will wish that more meaningful discussions had been held with Rudd immediately after the "coup", and they will debate whether there should have been better responses to the key Rudd question.

The Coalition on the other hand, will surely question policy responses to the Government's high speed broadband and their own unnecessarily generous parental leave scheme.

And the public will bemoan the absence of sharp policy differences more broadly, as well as the prospect of more elections being called down the track without a resolution ahead of time to fundamental issues like how debates are arranged and how costings are assessed.

By Saturday night - Australia will have its third prime minister in just under two months - or it will have given electoral endorsement to a woman for the first time. Either way, Saturday night will not be a short story. And it will be genuinely historic.

Barrie Cassidy hosts Insiders and Offsiders on ABC1.