Demonstrations are taking place across Australia as protesters call on new Senators to stop the budget.
A crowd of workers, students and pensioners have rallied in Sydney to send a message to new Senators about the unfairness of the Abbott Government's first budget.
It's estimated around 2,000 rally-goers, waving trade union flags and budget-protest placards, are converged near the city's Town Hall.
Greens leader Christine Milne told reporters on the scene the protest was borne out of frustration against planned federal cuts to health and welfare spending.
"(Tony Abbott) is making life harder for people," Ms Milne said.
"He's making life a misery for people who are unemployed and searching for work."
The Greens leader said incoming Senators need to listen to the community and block budget measures.
Several of the government's budget measures, including the $7 GP visit co-payment, changes to jobless benefits, a higher pension age and deregulation of university fees have been criticised as unfair.
Treasurer Joe Hockey has said the criticism has "drifted to the 1970s class warfare lines" and his budget was about equal opportunity, not equality of outcome.
"Our duty is to help Australians to get to the starting line, while accepting that some will run faster than others," he said in June.
But Unions New South Wales Secretary, Mark Lennon, says the budget is the most unfair attack on the living standards of working Australians in living memory.
He says if new Senators allow this budget through in its current form it will fundamentally reorient Australia, making us a less fair society.
"If they do decide to support the government, we will continue to campaign against this budget to make sure that we can restore fairness and equity to our social security system on behalf of all Australians".
Protesters also gathered across other Australian cities, including Melbourne, Adelaide, Canberra and Brisbane.
In Canberra, a few hundred people gathered at Parliament House while in South Australia, unions lead anti-budget rallies to state Parliament.
State Secretary of SA Unions, Joe Szakacs says the community is angry and afraid of budget measures.
"The community is also willing to stand up," he said.
"Right across Australia we're seeing tens of thousands of people today standing up against what is really a desperately unfair and mean federal budget."
"People together, people in our community together have the power to bust the budget and that's what they're overwhelmingly doing today."