Treasurer Wayne Swan believes Labor can and must win this year's election, warning that a Coalition victory would result in large-scale job cuts and public services being slashed.
In a speech to be delivered at the Australian Workers Union (AWU) national conference later today, Mr Swan will tell delegates that Labor is facing one of the toughest elections battles in many years.
"Many of the usual pundits have written us off. My advice is to not listen to them," Mr Swan will say.
"There's no sure thing in a two-horse race, especially when one of the jockeys is called Tony Abbott.
"We can win. We have to."
His speech comes a day after the release of , which showed the Coalition would win in a landslide if the results were replicated on election day.
It also comes after Prime Minister Julia Gillard .
There is also internal criticism of Mr Swan's performance as treasurer, following last week's initial refusal to rule out personal income tax hikes and later getting the unemployment rate wrong.
But he has sought to defend Labor's economic legacy, arguing the Government has successfully steered the country through the worst of the global financial crisis and grown Australia's economy at a time when others have shrunk or stagnated.
"I often think to myself, if only we'd got our chance when things were booming," Mr Swan will say, according to excerpts of his speech provided to the media.
"But whilst we all would have preferred the global financial crisis never happened, we should feel extremely proud of the things we have achieved together."
AWU national secretary Paul Howes they would be in the "fight of their lives" if the Coalition won the election, due to be held on September 14.
"The Liberals do not believe in a fair day's pay for a fair day's work. They do not believe in good Aussie jobs. They do not believe in looking after the battler," Mr Howes said.
"That's why we have to prepare ourselves for the fight of our lives."
Mr Swan will tell the AWU gathering that the Coalition has become "radicalised" by extreme right-wing political elements, similar to the Tea Party movement in the United States, and a Tony Abbott victory would mean a return to Howard-era workplace relations policies.
"The Liberals truly believe that the adversarial workplace relations system of the Howard government was the 'golden age'," he will say.
"They would rather see employer pitted against worker.
"Mark my words on this – whatever pledges Tony Abbott makes in blood, whatever he claims is dead, buried and cremated, whatever name he chooses for it, he will bring back the worst elements of WorkChoices."
Some Coalition MPs want to make substantial changes to the Fair Work Act, but Mr Abbott has previously said that any amendments will be "careful, cautious (and) prudent".