Workplace Relations Minister Bill Shorten has launched a passionate defence of unions, condemned the coalition for playing a game of policy "hide and seek" and taken aim at pessimists in the ALP.

Labor's fight to retain government at the September 14 election would be "very hard", Mr Shorten told the Australian Workers' Union national conference on the Gold Coast on Tuesday.

He told them the Australian Labor Party was Australia's "pre-eminent political party" and urged the union movement to "respect and support" Prime Minister Julia Gillard and Treasurer Wayne Swan.

Mr Shorten acknowledged some in the party were saying "it is all too hard, the polls are terrible, what can we do?".

But he had an answer.

"The time has come for us to explain to the Australian people that we stand alongside them, we stand in front of them, we stand for them, because we are the optimistic believers in the future of this country," he said.

Mr Shorten, a former national secretary of the AWU, waved his union membership card as he declared union members should be proud of who they are and what they deliver for members.

He said "vested interests" wanted to see an end to the union movement, saying it had passed its use-by date.

"When critics say the unions have had their day, you tell it to people who die at work, families of those victims, people who are being underpaid," Mr Shorten told the 500 delegates.

"It is logical and reasonable and sensible that Australian workers, in combination with employers, create the national wealth of this country and unions would seek the fair distribution of national income.

"How can this picture of society be out of date?"

Mr Shorten said that in the run up to the election, the political "scoreboard" was on the government's side as it had put 470 pieces of legislation through parliament since the 2010 election.

The minister said Labor needed to make it clear to voters that "politics should never be a game of 'the Liberals hide their policies and we seek them'".

"Hide and seek is not acceptable," he said.

"It is not good enough that the only things they have announced in workplace relations is union batting and union bigotry."