He was trying to differentiate himself from Opposition Leader Tony Abbott at Rooty Hill RSL Club. A woman with a worried look on her face asked Abbott about foreigners buying ''our'' land.

It was clear that we were talking about Chinese - perhaps Japanese - foreigners and that we were in populist country, working off the fear and loathing spread by Barnaby Joyce about a Chinese purchase of Cubbie Station, and about fears expressed elsewhere that Australian farms are being ploughed by sinister aliens.

Abbott, to his credit, gave a straight-down-the-line response - and without directly saying so, repudiated the nonsense seen occasionally to burble from the mouth of Joyce.

We welcome foreign investment - although if there is any occasion to suspect that it might not be in the national interest, a proposal can be referred to the Foreign Investment Review Board. Investors cannot, after all, take our land away. Abbott even manifested sensitivity to the implication that foreign investment was of particular concern when it came from China.

There has been no difference in approach to such issues between Labor and the Coalition - or at least the Liberal Party, and no particular occasion to pander to those who see foreign investment - particularly the purchase of agricultural land - as a sovereignty issue.

But Rudd could hardly help himself making an appeal to the populist vote. He said he was sometimes a bit worried - ''a bit nervous, a bit anxious frankly, about simply an open slather on this. I think when we come to rural land, but land more generally, we perhaps need a more cautious approach… I am looking very carefully at how this [recent buys] affects the overall balance of ownership throughout Australia.''

The implication was that on this issue, Abbott was some sort of doctrinaire free-marketeer giving away our sovereignty, while Rudd was a bit old-fashioned and inclined to fret that Asians were secretly stealing our very soil away. Not necessarily minded to interfere, of course, but to watch carefully lest they be up to some sort of inscrutable tricks.

So, if they were listening, or care, populist nationalists know they should vote for Rudd rather than that tool of international capitalism (and perhaps communism) Abbott.

The whole episode reminds me of the 1980s when the last populist - and racist - concern about Australia being taken over - in this case by the wicked Japanese - had politicians hopping every which way. RSL types were being dragged out to remember the war every time a Japanese company bought a golf course or a Gold Coast hotel; pinch-faced women would complain that Japanese tourists had their own guides and did not buy in their awful souvenir shops, and ratbags of the right and left were muttering darkly about foreign invasions or takeovers.

Japanese investors were also buying up big - indeed bigger - in Canada, and in the United States. They were paying top dollar, too - and causing considerable land inflation because, at the time Japanese exports were riding high, and Japan was awash with Yankee dollars.

The very stake in the American economy being purchased was giving Japan an interest in continuing American prosperity, rather than some sort of liquidation sale on the tremendous burden of American debt to Japan.

Alas, with or without such a stake, most investors were buying too high, and in due course went bust because the ''value'' of the land and houses they had bought fell. Such things are worth only what someone else is prepared to pay. And when one's foreign land investment becomes a liability, one cannot take it home to place ruefully on the mantelpiece. It sits there for the next sucker.

The next suckers, by and large, have been Chinese, with trillions in surplus cash, and, in many cases, very good reasons to diversify their investments, particularly when, in the First World, a sizeable land purchase can often shortcut the path to permanent residence rights. As with Japan, Australia is thought to be No.3 (behind the US and Canada) as a destination for these surplus dollars but, as with the US and Canada, it is thought Chinese land buying here is still well behind the amount of land buying by British and European interests. Oddly investment by Occidental roundeyes, or by those whom the worriers might describe as [white] ''people like us'', rarely causes anxiety.

Foreign buy-ups often overlap with mining, say of iron ore, and some seem to feel that the weight of the continent is dropping as minerals are being shipped away. Others worry that in due course Chinese landlords will turn their acreage into bok choy farms, exporting everything home, with ''ordinary, decent Australians'' starving, perhaps on the model of the Irish potato famine. From some people, I have seen indignation at the idea of purchase by aliens on an open market almost as strong as resentment of the idea that former landholders - Aborigines - might have some continuing rights in the acres from which they were dispossessed without compensation. It all goes to show there's not a backyard safe from strangers.

Rudd needs every vote he can get - and a good deal more - so it is perhaps not a surprise that the opportunity of pandering to this nonsense was a temptation. But that he could succumb to it is a good example of why he has pretty much forfeited the right to be taken seriously as a contender.

After such antics, one can withhold any support - even an ultimate preference - without a twinge of pity. As over asylum seekers, or seriously lunatic thought bubbles such as tax-free zones in the Northern Territory. Stuff so bad or so nutty that it can positively overcome any residual or instinctive loyalty.

Rudd is repeating the besetting sin of Labor of the 21st century. It is of thinking that the support of natural Labor, or leftist, voters can be taken for granted, and that they will understand why leaders have to play the populist ratbag, or promote wrong, immoral or plainly silly policies on the chance of votes from others. The problem is that a great part of the electorate no longer has any idea of what Labor stands for. They do not know the core values of the party - if it has any - any more. Most voters have not in their lifetimes even heard those values articulated, let alone practised. Particularly after Tampa in 2001, Labor voters came to see there was almost nothing Labor leaders would not say, or do, if they thought there was a vote to be had.

It's time the party was told - by its own - that enough is enough. Defeat and disgrace will speed the process.