Opposition Leader Tony Abbott has told a Coalition party meeting he has no illusions about how hard it will be to win the next election after today's Newspoll, which gave Labor a small bounce.

Telling colleagues their job would not be over until the election was won, Mr Abbott observed: "Gillard won't lie down and die, and where there's life, there's fight."

Julia Gillard is once again the nation's preferred prime minister and her government has received a small boost, according to the poll.

In caucus today, Ms Gillard attempted to rally her troops, saying this was  ''the hardest political time'' for the government.

Making reference to the Opposition's crusade against the carbon tax, she said it was ''easier to raise fear against the unknown, than the known''.

She said that she believed Mr Abbott was becoming ''increasingly'' desperate ahead of the July 1 introduction date of the tax.

Mr Abbott's personal support is at its lowest level since he won leadership of the opposition in 2009.

But both leaders have a way to go to win the public's approval, with 60 per cent of voters dissatisfied with the performance of Ms Gillard and Mr Abbott.

The Newspoll shows support for the federal government has inched its way to its highest level in three months. Its primary vote crept up two points over the past fortnight to 32 per cent, while the Coalition rose by one point to 46 per cent.

On a two-party preferred basis, the Coalition retains a virtually unchanged, election-thumping lead of 54 per cent to Labor's 46 per cent - a rise of 1 percentage point.

Deputy Opposition Leader Julie Bishop has attributed the poll result this morning to two factors.

Ms Bishop told the Coalition meeting that cheques had started to arriving in the mail as part of the government's carbon tax compensation and noted that whenever there was discussion about Kevin Rudd coming back, Labor's poll numbers rise "in anticipation".

Observing that NSW Labor general secretary Sam Dastyari had been briefing the media that Labor was not ready for an election, Ms Bishop warned her Coalition colleagues to be ready for the possibility of snap poll.

The Newspoll result represents a five-point rise in Labor's primary vote since the budget on May 8.

The  survey was conducted after a brutal week in Australian politics, in which the Coalition aggressively pursued MP Craig Thomson, who is accused of using union money to pay for personal expenses, including the hiring of prostitutes.

Mr Abbott and other Coalition figures have labelled Mr Thomson's speech to Parliament last week, in which he rejected all allegations, as "utterly implausible", and have referred the Labor exile to the privileges committee, with claims he misled Parliament.

Mr Abbott and other Coalition figures have labelled Mr Thomson's speech to Parliament last week, in which he rejected all allegations, as "utterly implausible", and have referred the Labor exile to the privileges committee, with claims he misled Parliament.

Mr Abbott and Ms Gillard engaged in a near week-long slanging match. Mr Abbott accused the Prime Minister of clinging to Mr Thomson's vote as a life-raft for her minority government, while Ms Gillard retorted that the Opposition Leader was playing a dangerous brand of gutter politics.

The result?

Ms Gillard has overtaken Mr Abbott as preferred prime minister with a bounce of four points, rising from 36 per cent a fortnight ago to 40 per cent.

Mr Abbott sank three points to 37 per cent. His personal support is now at its lowest level since he became Opposition Leader in 2009.

Overall, Ms Gillard and Mr Abbott were judged equally badly - with 60 per cent of voters saying they were dissatisfied with their performance.

The small measure of positive news for Labor comes ahead of today's caucus meeting, which some MPs have predicted will be "robust."

Cabinet unity took a hammering this week over the conflicting stories about the foreign worker agreement with mining magnate Gina Rinehart. Left-aligned MPs and senators are also expected to take issue with the changes to the single-parent payment revealed in the budget.

MPs of all stripes weighed in on the poll numbers - with some Labor figures less cheered than others.

NSW Labor senator Doug Cameron said the results were "still abysmal" and the "slight upturn" in the poll numbers were due to government measures to support people struggling with the rising costs of living.

"The Newspoll figures are still abysmal but they're getting better," he said.

Senator Cameron, who has been highly critical of the enterprise migration agreements announced last week, said he did not want to see "industrial apartheid' as a result of the program.

Parliamentary secretary Richard Marles said the uptick was because the public were turning off Mr Abbott, who he said was "a dog" of a candidate for the prime ministership.

Opposition spokesman for Immigration, Scott Morrison, said it was a harder task for an opposition to be seen as "positive" by the public.

The Coalition was not "worried" by the poll. But Queensland senator Barnaby Joyce ascribed the sustained attacks on Mr Thomson as a reason for the Coalition's slight poll slump.

Labor backbencher Kelvin Thomson spoke out against the foreign worker deal for a second day and warned Labor to "not get too excited with this poll".

Assistant Treasurer David Bradbury said: "People are seeing an Opposition Leader that is so desperate to try and bring a government down that they have formed an adverse opinion about how negative this bloke had become."

Gillard Won't Lie Down & Die, Says Abbott

meanwhile .....

The Department of Immigration is investigating claims that hundreds of Chinese workers on a massive iron ore project in Western Australia are being paid half what Australian workers on the site earn.

The Chinese workers on the Sino Iron project in the Pilbara are believed to be getting $70,000 to $80,000 for jobs for which Australian workers would be paid about $150,000.

It is the first investigation by the department into alleged underpayment at the site - despite repeated assurances by Canberra since September 2010 that any attempt to underpay foreign workers on the $5.4 billion project would be stamped out immediately.

Fury is growing in unions and the Labor Party over the approval on Friday by the Gillard government for 1700 foreign workers to be brought in to work on Gina Rinehart's $7billion-plus Roy Hill iron ore mine in the Pilbara.

The Sino Iron project, at Cape Preston near Karratha, 1500 kilometres north of Perth, is the largest magnetite mining and processing operation under construction in Australia, and is being built by Hong Kong's CITIC Pacific.

Department investigators went to the Sino Iron mine two weeks ago, 18 months after the Construction, Forestry, Mining and Energy Union first raised concerns about underpayment of between 250 and 300 Chinese workers.

The Fair Work Ombudsman last year audited the project, following up on the initial claims made by the union in 2010, but did not find any instance of underpayment of workers' lawful entitlements.

Attempts to contact CITIC Pacific last night about the allegations were unsuccessful.

A spokeswoman for the department last night said: ''The department takes any alleged breach of ... 457 sponsorship conditions very seriously.''

Employers who bring in workers on 457 visas are required by law to pay them the same market rate as Australians. But the union alleges Chinese workers are being brought in as skilled tradespeople, then given labouring work at cheaper rates.

CFMEU national construction division secretary Dave Noonan said if overseas workers were allowed to be brought in en masse for projects like Cape Preston, wages would be driven down and Australians would find it harder to get jobs in the resources sector.

''Already we see a situation where a lot of Australian workers are telling us they are applying for jobs on these projects and don't even get a call back,'' Mr Noonan said.

He said the Chinese workers who were brought out under the 457 visa program were meant to be skilled tradesmen, such as boilermakers. ''This is a rort; they are being used as labourers,'' he said. He said union officials had been unsuccessful in attempts to independently interview Chinese workers on the site.

The mine is on land owned by Queensland businessman Clive Palmer, who leases it to CITIC in return for millions of dollars of royalties once production is further advanced.

Mr Palmer said last night he did not believe the claims by the CFMEU.

''Most certainly they are not working for us - everyone who is working for us is getting top dollar,'' he  said.

''The critical point is whether these people are full-time 457 visa holders, which means they'd be resident here and entitled to be paid award wages.''

Foreign Mine Workers 'On Half Pay'