Opposition Leader Bill Shorten has claimed savings of $71 billion over ten years – most of it from rejecting almost all the budget’s company tax cut – as the battle over funding escalated.

Delivering his budget reply on the parliament’s last day before Malcolm Turnbull calls the election on Sunday, Shorten said Labor would oppose the tax cut for big business, continue the deficit levy on high-income earners, and crack down on dodgy private college providers.

He said the budget had tax cuts for high-income earners but nothing for families and “not one cent for ordinary Australians”.

“From Tony’s tradies to Malcolm’s millionaires – this is a budget for big business over battlers,” he said. “A working mum on A$65,000 with two kids in high school will be over $4700 worse off every year. And someone on $1 million will be almost $17,000 better off every year.”

He turned back the government’s attempt to paint Labor as class warriors. “This prime minister has the audacity to accuse us of waging ‘class war’. It is not ‘class war’ to disagree with cutting money from families on $50,000 and $60,000 in order to give millionaires a tax break.

“It is not class war to ask why he is cutting $80 billion from schools and hospitals – but spending billions on big business.

“It is not ‘class war’ for Labor to speak up on behalf of everyone this government has forgotten and betrayed – women, young people, pensioners, carers and veterans.”

Shorten said Labor would support the budget’s increase of the 37% tax threshold from $80,000 to $87,000.

But now was not the time to give the richest 3% of Australians another tax cut on top of this, nor to reduce the marginal rate for individuals who earn more than $180,000, he said. The Parliamentary Budget Office (PBO) estimated this would improve the budget by $16 billion over the decade.

Labor would support a tax cut for small businesses with a turnover of less than $2 million a year.

“We will deliver tax relief for the small businesses representing 83% of Australian companies. But billion-dollar operations are not small businesses,” he said.

“Labor will not support Mr Turnbull’s ten year tax cut for big business.” This would be a budget improvement of $49 billion over a decade, according to the PBO.

These two decisions made a $65 billion budget improvement, he said.

Shorten’s claiming of the savings followed Malcolm Turnbull being put on the spot in an interview on Sky when he refused to say what the budget’s enterprise tax plan – which would eventually drop the rate for all companies to 25% – would cost over a decade.

The government did not want to release the figure, which Treasury has estimated, because it was trying to make it harder for Shorten to claim the saving. But the tactic backfired.

The opposition seized on the issue in a fractious final Question Time of the parliament. Turnbull defended his position by saying it was “not the practice of the government or indeed governments to release itemised elements of the medium-term projections beyond the forward estimates”.

In his budget reply, Shorten in general embraced the budget’s crackdown on superannuation for the wealthy but said it had “very grave concerns” about the retrospective element.

He condemned rorting in the private system of vocational training. He said the pendulum had swung too far to private providers, and Labor would be backing public TAFE.

“We will restore integrity to the training system, by cleaning out the dodgy private colleges who have been ripping Australians off for too long. In 2014, the ten largest private training colleges in Australia received $900 million in government funding. Yet less than 5% of their students graduated.

“Tens of thousands of Aussies are being loaded up with massive new debt – but not the qualification they need to find a job.” Labor would cap vocational education loans at $8000 per student.

“We will cut this wasteful spending, saving an estimated $6 billion over the decade,” he said.

Shorten also promised a Labor government would legislate to protect Medicare within its first 100 days.

He said Labor might be the underdogs in the coming election “but we have never sought to be a small target”.

Michelle Grattan does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.