Rudd's lead - 70 per cent to Nelson's 17 per cent - puts him a vast 53 percentage points ahead of Nelson. It would appear to be an unbridgeable chasm.

"It's the biggest hammering in history," the Herald pollster, Nielsen's John Stirton, says.

It makes Simon Crean's worst performance against John Howard, a deficit of 42 percentage points, look positively respectable. That was enough to cost Crean his job as leader of the opposition.

So should Nelson's dreadful polling cost him his grasp on the same job now?

On the face of it, the answer must be yes. But there is a big question for the Liberal Party to answer before it decides: is Nelson in a hopeless position because he is unsaleable, or because Rudd is unassailable?

The dominant reality in Australian politics is the ascendancy of Kevin Rudd. Today's poll finds he is the second most popular leader in the history of the Nielsen poll, the longest polling series in Australia.

Rudd's approval rating is 69 per cent. For perspective, the highest rating Gough Whitlam managed was 62 per cent; Malcolm Fraser's best was 56; Paul Keating's was 40; John Howard peaked at 67.

The only leader to rate higher than Rudd was Bob Hawke with 75 per cent, and it took him more than a year and a half in power to get there.

"The key thing to understanding what's going on is Rudd's extraordinary popularity," says Stirton. "Howard was the most popular leader the Liberals had in a generation, and he was still popular when he lost. If Howard struggled against Rudd, there's no way Brendan Nelson or Malcolm Turnbull will do any different in the short term."

This is not to say that Nelson is polling well. He is not.