The steady influx of migrant workers that helped sustain Australia's long boom has all but ended.

The Federal Government is predicting a 30 per cent drop in the number of migrants this financial year, and an 85 per cent drop in 2020-21 (compared with 2018-19).

Some argue the coronavirus-induced slump offers an opportunity to rethink Australia's migration program.

In a May 3 opinion piece, Labor's immigration spokesperson, Kristina Keneally, said Australia should have a "migration program that puts Australian workers first".

"Our post-COVID-19 economic recovery must ensure that Australia shifts away from its increasing reliance on a cheap supply of overseas, temporary labour that undercuts wages for Australian workers and takes jobs Australians could do," Senator Keneally wrote.

But the Federal Government has rejected the argument that migrants have been taking jobs ahead of Australians.

In an interview on ABC Radio National about Senator Keneally's article, Minister for Population, Cities and Urban Infrastructure Alan Tudge said the Coalition had scrapped the previous program for skilled temporary migrants, the 457 visa, because it had not been operating as it should under Labor, including "bringing in people to flip burgers".

Mr Tudge said the Government had introduced a Temporary Skill Shortage (TSS) visa, and brought in new rules to ensure Australian workers are prioritised over foreigners for available positions.

"We've always been very, very careful to prioritise Australians and Australian jobs," Mr Tudge said.

"We scrapped the 457 visa program when we came to office, we introduced labour market testing so the Australians would be prioritised for the jobs available."

Is it correct that Australian workers are being prioritised for jobs available? RMIT ABC Fact Check investigates.

He homed in on a specific type of visa — the Temporary Skill Shortage visa — to make the case that Australian workers are being prioritised.

The labour market testing rules referred to by Mr Tudge, requiring employers to advertise locally before hiring temporary foreign workers, apply only to the TSS visa, and even then there are significant exemptions.

For example, labour market testing is not required when it would conflict with Australia's international trade obligations.

That means it does not apply to workers from China, Japan, Mexico, Thailand, Vietnam, Canada, Chile, South Korea, New Zealand or Singapore.

Moreover, the TSS visa represents a relatively small and shrinking proportion of the total number of visas issued in any given year that include work rights.

There are many exemptions to labour market testing requirements.(Neroli Roocke)

Whether the growing numbers of foreign workers with other types of temporary work visas — for example student visas or working holiday visas — have been undercutting wages and jobs that could be filled by Australian workers is not a simple question.

Some studies suggest skilled migration has had little if any impact on wages or employment. 

Others suggest growing numbers of predominantly low-skilled workers, for example on student or working holiday visas, could be undercutting wages and employment, particularly for younger people.

But any evidence is anecdotal. As experts have pointed out the data is "ropey", partly because employers and some migrant workers are unlikely to report the underpayment of minimum wages.

This makes assessing the impact of temporary migration — skilled or otherwise — problematic.

The verdict: Mr Tudge's claim is not the full story.