Treasurer Jim Chalmers was forced to halt a keynote speech about the nation's finances when environmental protesters twice crashed the stage.

Dr Chalmers had just begun his speech at the Queensland Media Club on Tuesday afternoon when a man appeared behind him carrying a sign which read: 'No new coal or gas'.

The Treasurer appeared to almost jump in fright as he spun around to see who was approaching, and broke off his address.

'Australia cannot afford any more climate disasters... When will the Labor Party stop funding more coal and gas projects?' the protester shouted.

Regaining his composure, Dr Chalmers said 'thank you mate, off you go' as a security staffer bundled the man off stage.

However Dr Chalmers had only just re-started his speech when another protester appeared on stage moments later carrying the same sign. 

'Mr Chalmers, I went eight days without power,' the female protester said as she was shepherded off the stage.

'Young people in this nation are going to suffer for the rest of their lives. When is Labor going to stop funding and approving new coal and gas?' 

The usually-unflappable Dr Chalmers let out a nervous laugh as he resumed reading from the autocue. 

His speech warned that the clean-up costs and the impact on the economy from ex-Tropical Cyclone Alfred could hit GDP by up to $1.2 billion. 

Dr Chalmers' also sought to downplay expectations of any major policy changes in next week's pre-election budget, as most of the policies 'have already been announced'.

These include the $8.5 billion investment in strengthening Medicare, the $7.2 billion for upgrades to the Bruce Highway and wiping up to $19 billion in student debt for up to three million graduates.

Prime Minister Anthony Albanese had been widely tipped to call the election for April 12, before storm Alfred scuppered those plans.

It will now be held in May, meaning next week's budget must be handed down - a situation an April election would have avoided.

The government had already announced most of its spending measures, on the understanding that it would not need to hand down a budget.

'This is more than we’d typically unveil before the Budget,' he said on Tuesday.

'And there’ll be provisions in the Budget for policies we will announce in the campaign, not next week.

'All this means there will be fewer surprises on Budget night.'