In an opinion piece written to coincide with Australia Day, Mr Swan laments that the republican movement has ''fallen from the national agenda over the past decade''.

''I think our national conversation is sold short when it doesn't include a debate about our relationship with the Crown,'' Mr Swan wrote.

The former leader of the Australian Republican Movement, Malcolm Turnbull, said it was never a bad time to talk about Australia becoming a republic, but he had mixed feelings about Mr Swan pushing the cause.

''While I am a committed republican, my heart sinks at the thought of Wayne Swan bringing his advocacy skills to such an important national cause,'' Mr Turnbull said.

In Mr Turnbull's view, the success of the republican movement turned on the longevity of the Queen. ''As someone who has considerable experience in not winning constitutional referendums, they are easier to defeat than to win and timing is everything,'' Mr Turnbull said.

''I remain of the view … that a referendum will not be successful prior to the end of the Queen's reign,'' he said.

In the 1999 republic referendum, 55 per cent of Australians voted that Australia should remain a monarchy.

The conservative movement to preserve Australia's link to the monarchy was led by Opposition Leader Tony Abbott.

The Australian Republican Movement's national director, David Morris, said republicanism had been off the agenda since the referendum because of a ''complete lack of political leadership''.

Mr Morris said the movement was launching a new campaign, with the slogan ''Our identity: who do we want to be?'' and would focus on Australians ''growing up'' and gaining their independence.

Meantime, ''flag advocacy'' group Ausflag have unveiled a new Australian flag to be used at sporting events, with the group labelling the existing flag ''confusing and embarrassing''.

Ausflag chairman and former NSW Nationals MP Robert Webster said last year's London Olympics had proved a tipping point.

"One of the most embarrassing moments was the flag raising ceremony at the 2012 London Olympics, following the women's pair rowing event ... all to the dulcet tones of God Save the Queen. UK first. Australia second. NZ third. It looked like Mother England teaching her kids how to fly. Or as one person summed it up in a letter to the editor in the Sydney Morning Herald (3 Aug 2012): "Britain, Little Britain and Littler Britain. Wake up Australia and get some pride".

Mr Webster said Ausflag would promote the new sporting flag at international sporting events, ''wherever our resources permit.''