As the iron ore price falls faster than Joe Hockey's popularity, a new analysis offers little optimism on the direction of Australia's biggest export-earner.

After a tough year selling his first budget, the treasurer's next effort on May 12 will be challenged by a steep fall in the iron ore price, a commodity he says has no apparent floor in sight.

Four months ago, Mr Hockey was trying to balance the budget with revenue based on iron ore at around $US60-a-tonne, itself a downgrade from $US95 in last year's budget.

But now he is factoring in a price of just $US35-a-tonne, a potential $A25 billion revenue loss over four years.

And the pain might not stop there.

The World Bank predicts a further economic slowdown in China - Australia's No.1 trading partner and main buyer of iron ore for steel making - over coming years.

New figures released on Monday also showed China's imports fell 12.3 per cent in the past year.

But the government won't be chasing down the revenue loss, opting instead to pursue growing export opportunities in Asia.

"We're not going to be imposing new taxes in order to try and recover that lost revenue," Mr Hockey said from New York, where he is en route to Washington for G20, IMF and World Bank meetings this week.

Despite the bleak outlook for revenue, Prime Minister Tony Abbott continues to promise a budget that will deliver good news for families and small business.

"The assurance that I give you is that we aren't going to tackle our budget problems at the expense of families' budget problems," he said.

But Opposition Leader Bill Shorten says the government never had a plan when it was elected in 2013, viewing Australia as a quarry that would ensure the good times rolled on forever.

"Since the last budget, business confidence in Australia has been in the toilet, we've seen unemployment go up, and now a dollar Australian will barely buy a dollar New Zealand," he said.

A new Fairfax-Ipsos poll shows voters aren't impressed with the Mr Hockey's performance either, with his approval rating slumping over the past 13 months from plus 20 per cent to minus 25.

But while they might not like the messenger, voters still say the coalition is the better economic manager at 41 per cent to Labor's 32.