An Advertiser poll reported 51 per cent of South Australians backing a republic, with 40 per cent opposed to change. At the same time 81 per cent believed a republic was inevitable. The Advertiser headline was ''Voters want to dump the Queen''.

Now consider two more surveys. The Australian Election Study has studied the issue at each federal election. The investigators at the ANU conclude that support for a republic has remained at about 60per cent for the past 10 years, since before the referendum. That was the figure in 2007. The question asked was, ''Do you think that Australia should become a republic with an Australian head of state or should the Queen be retained as head of state?'' In the same survey 64per cent thought the Queen and the royal family were not very important to Australia. Only 11 per cent thought they were very important (presumably the same people as the 10 per cent who strongly support the monarchy).

UMR Research reported last November that, in answer to the simple question ''Do you support or oppose Australia becoming a republic?'' 50 per cent supported it and 28 per cent opposed it (almost 2:1). Men supported a republic by 58per cent to 24 per cent, while women (43 per cent to 32 per cent) were not as convinced. That gender difference has long been the case.

All polls report more republicans than monarchists (a plurality) and most polls report a republican majority of the whole population of about 3:2. Republicans have strong support (60 per cent) and, therefore, should win a general plebiscite. But realistically they need to increase that general support to the region of 65 per cent to 70 per cent to be confident of achieving a double majority in a referendum.

Do republicans care enough?

One weakness of the republican movement has been the relatively low intensity with which a republic is supported. To take the AES survey, for instance, only 31 per cent of respondents strongly support a republic, about half of all republicans. On the other hand only 10 per cent of respondents strongly favour retaining the Queen, or about a quarter of all monarchists.

Another continuing weakness is internal disagreement about the type of republic, one of the key issues at the 1999 referendum. In the AES survey, 80 per cent favour election of the head of state by voters (50 per cent strongly favour so-called direct election). In the UMR survey, exactly the same figure (80 per cent) want a president elected by the people. These figures send a strong message about the power of direct election.

Another way of measuring the trajectory of public opinion is to investigate the opinions of younger people. The Morgan Poll reckoned younger Australians were more inclined to the monarchy, but that is certainly not the general view.

UMR Research reported that those under 30 supported the republic most clearly (49 per cent to 18 per cent) but, as other polls such as Newspoll have also reported, not only because they were more republican than the rest of the community but because of another crucial factor.

Not only are younger Australians less monarchist than older age groups but a much larger percentage of the younger electorate is undecided either way. In a January 2006 Newspoll a huge 29 per cent of younger people were undecided.

To be successful, republicans must connect better with those under 30 because that is the demographic Kevin Rudd and Malcolm Turnbull will be watching most closely.

John Warhurst is an adjunct professor of political science at the ANU and senior deputy chair of the Australian Republican Movement.

John.Warhurst@anu.edu .au