In a rare intervention into politics, the heads of St Vincent de Paul Society, Mission Australia, Catholic Social Services, Anglicare and the Salvation Army have combined to call out the "injustice" of removing the energy supplement on benefit payments to new recipients.

The change, contained in the government's $6 billion omnibus savings bill in front of Parliament, will cut the Newstart Allowance by about $5 a week for new recipients and lower the rate of pensions and family payments accessed by a total of 2.2 million people, if it becomes law.

At just $38 a day, Newstart equates to 39 per cent of the minimum wage and is the second lowest unemployment benefit among OECD countries on a comparative basis.

Charities will unite in a press conference on Sunday to highlight the "unfairness" of the government removing the energy supplement, which was introduced as part of the carbon tax compensation package in 2011, while at the same time pushing ahead with nearly $10 billion in personal and company tax cuts promised by Prime Minister Malcolm Turnbull during the election campaign.

John Falzon, chief executive of St Vincent de Paul, said: "It's the height of injustice and unfairness to take away from these people who have the least while seeking to give tax cuts to those who have the most.

"It's deeply divisive and benefits those who are already well off. It's time both sides of politics unite to ensure those left out of the job market are not pushed further below the poverty line."

Mission Australia chief executive Catherine Yeomans compared the controversial picture of Mr Turnbull handing $5 to a homeless man to the reality of Mr Turnbull and Treasurer Scott Morrison taking $5 a week from people joining the almost 800,000 Australians on Newstart.

"I think most Australians probably assume there is a reasonable social security safety but the reality is there is not. There should be community outrage at taking from the poorest people like this," she said.

Cassandra Goldie, head of the Australian Council of Social Service (ACOSS), said Mr Turnbull had promised he was listening after narrowly surviving the election.

"Who is he listening to?" she said.

"Not the people in regional areas. Not the people in Tasmania where there are hardly any jobs. This is not about people being lazy, this is 800,000 people who cannot find a job."

She said ACOSS is aware of parents who are going without meals to ensure the internet is kept on for their children and others who cannot afford $10 so their kids can play weekend sport.

KPMG recently urged the government to raise the dole by $50 a week and the Business Council of Australia has said Newstart "no longer meets a reasonable community standard of adequacy".

Mr Morrison has insisted that abolishing the energy supplement, which will save $1.3 billion by 2020, is justified because it "compensates people for a tax that no longer exists".

But welfare advocates point out that the billions in tax cuts for the employed, also introduced alongside the carbon tax, are not being revoked.

The intervention of charities on Sunday comes as the Labor caucus, which is divided on the issue, is due to discuss support for removing the energy supplement when Parliament resumes on Monday.

Shadow Treasurer Chris Bowen resolved to support the budget savings measure as he sought to tighten Labor's bottom line during the election but senior members of the Left, including Bill Shorten's leadership rival Anthony Albanese have spoken forcefully agains the idea of backing a measure that has been compared to some of the controversial items of the infamous 2014 Hockey-Abbott budget.

Along with Jenny Macklin, the Opposition spokeswoman for families and social services, Mr Albanese has been arguing internally and in public that the ALP need not be locked into its election savings promises because they were part of a package that included support for apprentices and skills training that the government has no intention of implementing.

In its submission to the hurried inquiry into the omnibus bill, Catholic Social Services, which provides services to 450,000 people, said: "Placing the burden of budget repair on those who can least afford it, while providing tax cuts to the wealthy and businesses, is wrong morally and economically."

$5 a big difference

There are times when Patricia Young is forced to ask her supervisors whether she can go to the freezer and take home a meal to feed her and her 15-year-old son.

The humbling request for the single mother from Merrylands is made a little easier in that the frozen meals are at the Salvation Army in Auburn, where she is a member of the work-for-the-dole scheme in the Salvos' restaurant.

Ms Young, a qualified hairdresser, said she knows the value of the $5 a week the government is proposing to cut from the Newstart Allowance for new recipients.

"Some people think 'it's just $5 so what's anyone complaining about?' but there are times when I will be down to the last $5 in my wallet and there are still two or three days until payday," she said.

"Working at the Salvos, if I am having a really bad week I can ask to grab a meal from the freezer but it is not nice to have to ask for help. You start to feel like you're not doing your job as a parent."

Having been moved off a parenting payment on to Newstart and the work-for-the-dole program, Ms Young has struggled to get hairdressing work because she has been unable to agree to work Thursday nights and Saturdays as the only carer for her son.

Keith Fernandez, a colleague of Ms Young's in the restaurant, has been on Newstart for eight years since losing work as an IT consultant.

"If you're out of work for more than six months in that industry you may as well kiss goodbye to getting another job," he said.

Mr Fernandez said the value of $5 is clear in the Salvos restaurant.

"If you're basically homeless you can come in here and get a three-course meal for $2. So that's two meals they are taking away for some people," he said.

Sean Smith, 40, who was moved off sickness benefits on to Newstart after his career as a postie was ended when a driver backed into his bike, hospitalising him for three months, said he struggled to survive despite living in a granny flat at his parents' house.

He had to borrow petrol money from his father to make an interview in Newcastle as he searches for work in the hospitality industry, he said.