The two former Labor leaders last shared a platform on the same day in 1991, when Mr Keating resigned as treasurer to challenge Mr Hawke for the prime ministership.

"The economy is Labor's," the pair told The Sydney Morning Herald and The Age in a statement conceived some weeks ago as they met to overcome decades of bitterness in their relationship.

The pair used their endorsement of Mr Shorten to claim sole credit for Labor in opening Australia's closed economy to become a modern, market economy.

By claiming that Labor can't manage the economy, Prime Minister Scott Morrison was arguing that Labor "can't manage its own creation - a dubious proposition even for him," they write.

In a pointed attack on Mr Morrison less than two weeks out from the May 18 election, Mr Hawke and Mr Keating claim the Liberal Party has "completely given up the economic reform agenda".

"And just as we modernised the economy in the face of the challenges of the day, Shorten's Labor is the only party of government focused on the need to modernise the economy to deal with the major challenge of our time: human induced climate change," they write.

Professor emeritus of politics at Sydney University, Rod Tiffen, said that it had taken the two former prime ministers nearly three decades to overcome their bad blood "shows how deeply personal the antipathy ran, but also how strongly they feel about the coming election".

While they have appeared together at Labor election campaign launches in the past, they have not spoken. "They now want to highlight that they are more united than divided, and more united than the Liberals," Mr Tiffen said.

Mr Hawke, 89, is too frail to travel by air and did not leave his Sydney home for the Labor campaign launch in Brisbane on Sunday but sent a statement of support.

Mr Keating appeared at the launch with Kevin Rudd and Julia Gillard, another pair who have had to grapple with personal bitterness in the years since Ms Gillard successfully challenged Mr Rudd for the prime ministership in 2010.

The Liberal Party claim to be the superior economic manager is the central theme of Mr Morrison's campaign. The Coalition leader hopes to prevent a Labor victory by targeting Mr Shorten's proposed changes to negative gearing, capital gains tax, dividend imputation and superannuation.

"The reality is it's not a reform it's just a tax grab. When you can't control your spending, that's when you go and hit people with taxes," Mr Morrison said on Tuesday.

Polling for many years has shown that the Liberals enjoy a persistent "brand" advantage in popular perception as the better party of economic management. Australia's last recession occurred in 1990-91 during the Hawke-Keating years.

In their statement, the two former leaders claim full credit for the Labor Party for Australia's 28 years of continuous economic growth. They said their governments turned the closed "fortress" economy they inherited in 1983 into a flexible, open economy.

"Almost 30 years of strong compound economic growth has produced what you would expect it to produce - a massive increase in national wealth. And that wealth has seen a 70 per cent increase in real wages since the reforms of the late 1980s and early to mid-1990."

Mr Hawke and Mr Keating allow the governments of their Liberal successors John Howard and Peter Costello credit for only one significant reform - the introduction of the GST.

Professor of public policy at ANU, economist Warwick McKibbin, commented: "I don't understand the basis for the argument - you've had reforms under Labor and the Howard government continued the reforms.

"And some of Bill Shorten's policies contradict the Hawke-Keating reforms.

"The Shorten plan to re-regulate the labour market, the change to the minimum wage, are moving backwards from the Hawke-Keating reforms."

Mr Howard has long argued that the Labor reforms were only possible because the Liberals in opposition voted to support key Hawke legislation.

Mr Hawke and Mr Keating attack the Coalition program on offer at next week's federal election as "economic obscurantism".

"The government is "seeking to employ 19th century technology in energy, failing completely to understand the economic imperative of climate change and the galloping opportunities of the digital age," they write.