SUPPORT for an Australian republic is at its lowest level since the mid-1990s as growing ambivalence on the need for a home-grown head of state saps the nation's will for constitutional change.

With renewed interest in the monarchy as the royal wedding approaches, a special Newspoll puts support for a republic at just 41 per cent, with only 25 per cent strongly in favour.

According to the poll, conducted exclusively for The Australian this month, overall support for a republic is now 10 points below a pre-referendum peak of 51 per cent, and at its lowest for 17 years since hitting 39 per cent in March 1994.

The latest poll reveals 39 per cent of Australians are against a republic, while one in five have no opinion either way.

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The results reflect a lack of enthusiasm for a republic among the nation's political leaders, even those who identify themselves as republicans.

But any mention of Prince Charles, and to a lesser extent his son Prince William, fires public support for an Australian head of state. The poll of more than 1200 voters found 48 per cent of respondents would back a republic with Charles on the throne and his wife, Camilla, as princess consort, while the proportion opposed falls to 34 per cent.

While Prince William and his bride-to-be, Kate Middleton, are more popular, 45 per cent of respondents said they would be in favour of a republic if William became king, while 39 per cent said they would be opposed.

The Newspoll reveals support for a republic is highest among middle-aged voters, with 48 per cent of those aged 35-49 in favour.

The over-50s are more likely to be opposed, while 18- to 34-year-olds are increasingly undecided. Men are much more likely to back a republic, with 49 per cent favouring the change compared with 34 per cent of women.

There is also a clear split along party lines, with Labor voters preferring a republic two to one over Coalition supporters.

Australians for a Constitutional Monarchy convenor David Flint said there was a lack of passionate support in the community for a republic, which politicians had responded to by shelving consideration of the issue.

He said support for the monarchy would continue to grow, even after the death of the Queen, 85, predicting an "enormous retrospective" on her reign when it came to an end.

"They'll call it the second Elizabethan age. It'll be quite astounding," Professor Flint said. "And then the interest will come up about the coronation and the next Prince of Wales and the sons and daughters of the Prince of Wales."

Australian Republican Movement chairman Mike Keating lamented what he saw as a lack of political leadership on the issue.

"All sides are looking for some sort of cheap political advantage, preferably next week," he said. "That's not the kind of issue the republic is. It's not about scoring cheap political points."

Major General Keating said public fascination with the royal wedding was a symptom of modern celebrity culture.

"We're interested in the goings-on of footballers and Russell Crowe and everyone else," he said.

"That's quite different to the concept of having a republic."

Read more about Australia's lack of enthusiasm for a republic at The Australian.

Originally published as Support for republic drops to 17-year low