The Abbott government’s budget has given Labor back its voice. That’s Opposition Leader Bill Shorten’s message to party members.

“This terrible budget of the Abbott government, it has defined the Labor Party,” he told the Victorian ALP state conference in Melbourne on Sunday.

“Friends, the Labor party nationally has its voice back.”

Mr Shorten used the speech to continue his attack on the coalition government’s first budget, warning Labor will stand up for those losing out.

His fury is directed at doctor co-payments, a raised pension age, restrictions on unemployment benefits, cuts to state funding and the fuel excise.

Mr Abbott’s “juvenile” paid parental scheme is also high on Mr Shorten’s hit list, with the Labor leader claiming it will give millionaires $50,000 they don’t need.

“See how that goes for pensioners trying to get an extra smear of Vegemite on their toast on day 13 of their budget,” he said.

Mr Shorten reiterated Labor’s fierce opposition to the $7 co-payment to visit a GP on Sunday and told the conference not even a cure for cancer would justify breaking Medicare.

Revenue raised from the co-payment will be fed into a medical research fund.

“But how dare you say that a cure to cancer is dependent upon wrecking Medicare,” he said.

“You don’t heal the sick by taxing them.”

State and territory leaders held an emergency meeting in Sydney on Sunday to discuss an $80 billion hole in state budgets left by last week’s budget.

Mr Shorten accused the government of using cuts to state funding for schools and hospitals to sneak in another tax.

“They are actually increasing taxes through the back door,” he told party members.

The states will have no choice but to raise GST because they must continue to operate schools and hospitals, he said.

Labor call it blackmailing, a line reiterated by the Greens.

“Even a crocodile wouldn’t swallow what Tony Abbott’s dishing up at the moment,” Mr Shorten said.

While Shadow Treasurer Chris Bowen says Labor will engage in debate about the GST, he won’t commit to supporting it.

The Greens have ruled it out completely.

Treasurer Joe Hockey said the government would honour its pledge not to change the GST in this term of government.

However, the measure would be considered by a planned review of the taxation system.