Saul Eslake warns Joe Hockey - your budget is in trouble.

One of Australia's most respected economists says Joe Hockey's budget is in deep trouble.

Saul Eslake, chief economist at Bank of America Merrill Lynch, says if the government's cost-cutting measures remain blocked in the Senate, the budget will still be in deficit by over $18 billion in 2017-18.

The most recent budget forecast a deficit is less than $3 billion in 2017-18.

While that's not necessarily enough to jeopardise Australia's AAA credit rating, Saul Eslake says it could leave Australia exposed to any global shock.

Here's what Dr Eslake told me on this morning's edition of AM.