Chris Bowen has defended Labor's plan to run bigger deficits over the next four years if it is elected, while admitting that "yes, Australia's AAA rating is under threat".

And he has promised Labor will unveil additional budget savings measures in a matter of days that won't be popular.

The shadow treasurer has moved to ramp up pressure on Treasurer Scott Morrison, arguing the threat to the credit rating is a problem for both major parties and that Labor will do more over the long term to repair structural problems in the budget.