For more than two years, Rod Cameron's pessimism about Labor's prospects has been a strictly private affair. Although he dubbed Tony Abbott unelectable, the former ALP pollster remained circumspect on the challenge facing the party he served in more than 50, mostly winning, state and federal campaigns.

''I didn't want to throw any curve balls in while there was a prospect that the party would do what I thought it would do - and that's just act out of self-interest,'' Mr Cameron explains. Now, ''more in sorrow than anything'', he is predicting an epic Labor disaster.

He is not alone. While the mood of the Labor caucus has been despondent for months, it seems that only now, 100 days from polling day, the gravity of what is in prospect is really sinking in.

For Mr Cameron and many others, the party's failure to return to Kevin Rudd, when the message from the polls was that he could restore Labor to a competitive position, has been an act of insanity that threatens Labor's existence.

''The majority of the modern Labor Party - the caucus, the leadership, the machine and, importantly, the union bosses who now dictate policy - has totally lost the plot,'' is how he expresses it.

''When they reaffirmed Julia Gillard's leadership, they really were turkeys voting for Christmas - and what a Christmas it will be. It will be a total wipeout in the outer suburbs of all the capital cities and the regional and rural areas to boot.''

There's not much time left for Labor to turn to the polls around.

Maxine McKew, the giant slayer who defeated John Howard and became a Rudd loyalist, agrees. ''What is being played out now is an absolute tragedy,'' she says. ''Labor has been in tight fights before and had its back to the wall, but I don't think we've ever experienced anything quite like this.''

Similarly perplexed is Barry Cohen, a minister in the Whitlam government, who anticipates an even worse result on September 14 than Gough Whitlam suffered in 1975 and 1977. Mr Cohen cannot fathom why backbenchers aren't petitioning Ms Gillard to step down for a fresh face, suggesting Bill Shorten would at least offer the prospect of a ''reasonable defeat''.

But it isn't that simple. Those who will soon face the voters can be divided into three camps: those, such as Ms Gillard and a swag of senior ministers, who are behaving as if a real contest still beckons; those who will support a return to Mr Rudd if the opportunity beckons; and those resigned to defeat but utterly opposed to Mr Rudd.

''You have to put yourself in the position of each caucus member,'' is how one former MP puts it. ''Yes, you're desperate. Maybe you're resigned to a crushing defeat, and still slightly self-delusional that you may buck the trend. And you ask yourself: 'Do I support Kevin again? Does he deserve it?'''

One perspective inside the Parliament is that the antics this week of Joel Fitzgibbon, Senator Doug Cameron and, more subtly, of Mr Rudd himself are as treacherous as they are unhelpful. Another is that they are an understandable reflection of a situation that is almost entirely of Ms Gillard's making.

Internal perspectives don't change the assessment of Rod Cameron and other outsiders of what is likely to happen in September. He thinks caucus ''will be reduced to a rump in the low 30s, and that's both number of seats and primary vote. And the new leader will take over a trade union party with a policy outlook totally at variance with the values … of the great majority of Australians.''

Tellingly, Mr Cameron now describes Mr Abbott as the ''hitherto unelectable'' Tony Abbott. ''I'm afraid I'm going to have that stamped on my gravestone - that I declared him unelectable.''

One difference between the loss that beckons and past defeats, he says, is that Ms Gillard is in denial on the extent to which she is responsible for Labor's low stocks.

Inside the PM's bunker, there is steely confidence that a campaign built around education, disability reform, the national broadband network and economic management will yet produce a contest.

The only certainty, come September 15, is that there will be much to reflect upon.

Ex-Labor Pollster Tips 'Epic Disaster'