Federal Treasurer Joe Hockey is set to lead a renewed push for Australia to become a republic, raising the ire of some of his Coalition colleagues.

Mr Hockey and Labor senator Katy Gallagher are forming a Parliamentary Friendship Group to revive debate about the issue, which has been effectively dormant since the failed 1999 referendum.

Key points: Joe Hockey, Katy Gallagher to revive debate through Parliamentary Friendship Group

Joe Hockey, Katy Gallagher to revive debate through Parliamentary Friendship Group Treasurer supported 1999 referendum

Treasurer supported 1999 referendum Announced by Australian Republican Movement head Peter FitzSimons

Announced by Australian Republican Movement head Peter FitzSimons Republic process should begin within five years: FitzSimons

The announcement was made by Mr Hockey's friend, and the head of the Australian Republican Movement, Peter FitzSimons at the National Press Club.

But the timing of the announcement has surprised some within Government, given the Coalition has struggled in recent months to maintain focus on its agenda of jobs and economic growth.

Mr Hockey's Cabinet colleague, Deputy Prime Minister Warren Truss, said a renewed debate on the monarchy was not on his list of priorities.

"We've got important issues to deal with, like the economy and managing difficult international issues, the security of this country. I think those are the sorts of things I'll be giving my priority to," he said.

"I think we've dealt with [the republic debate] in the past, I suspect public opinion hasn't changed much, so let's concentrate on the things that matter most to this country."

The Treasurer supported the 1999 referendum and is one of the most prominent republicans in Government, along with Cabinet colleague Malcolm Turnbull, who led the Australian Republican Movement before entering Parliament.

Liberal senator and constitutional monarchist Dean Smith criticised Mr Hockey, saying it was "most definitely a distraction".

"The priority for every parliamentarian is to focus on the national economy and on jobs creation, nothing is more important than strengthening the economy and creating jobs at this time," he said.I

However, Mr Hockey defended his decision, saying he had long advocated his views on a republic.

"They are a matter of public record and those views haven't changed," his spokeswoman said.

ACT Liberal Senator Zed Seselja came to Mr Hockey's defence.

"Joe Hockey's views on this are well known, I happen to share those views," he said.

"I think, whilst it's certainly not a top-three issue, it's an important discussion to have and Joe's free to lead the charge."

Opposition Leader Bill Shorten said he believed Australia was "smart and mature enough" to have a debate about an Australian head of state.

"It's time for Australia to become republic and I welcome the support of anyone — including Joe Hockey — in helping this happen," Mr Shorten said.

"If only he could convince his Prime Minister to think of the future for a change and not remain stuck in the past."

Fitzsimons: 'We're putting the band back together'

FitzSimons said in his Press Club speech: "The key thing I wish to say today is we are putting the band back together."

Politics in your inbox Subscribe to get ABC News delivered to your email, including top politics headlines, plus the day's top news and analysis and alerts on major breaking stories.

"It's the hope in the next five years, Australia can begin the formal process towards becoming the Republic of Australia.

"A republic that we deserve to be, an independent sovereign nation beneath the Southern Cross we stand, a sprig of wattle in our hand."

In 2004, Mr Hockey described the then-Labor leader Mark Latham's push for another republic referendum as a "distraction".

"When you've got hospitals and schools and police and security as you talked about — the issues that really matter — including national security, Mark Latham is off talking about the republic and as an avowed republican, I don't know where he's coming from," he told Lateline at the time.

In that interview, he said if another referendum were to be held "let's get it right and let's get it up".

'Minimalist model' proposed for referendum question

Two reasons are often cited for the failure of the 1999 referendum: the wording of the question, and a brawl within the republican movement over whether the head of state should be elected by politicians or the people.

To avoid these problems, FitzSimons proposed a "minimalist model", starting with a simple question to be put to the Australian people.

He said the question should be: "Do you support replacing the British monarch with an Australian citizen as the Australian head of state?".

Under his proposal, the Prime Minister would still appoint a Governor-General, but rather than asking the Queen to approve the appointment, it would be signed off by a two-thirds majority of Parliament.

"When properly presented, my minimalist model — this is only my view — is the most likely to succeed as it addresses the foremost concern of the 'if it ain't broke, don't fix it' crowd," he said.