The shadow treasurer, Jim Chalmers, has ruled out reviewing Newstart in opposition, saying those hoping for a boost to the payment had Labor won the election will now “have to convince the government.”

As Labor prepares to reshape its policy agenda following its 18 May electoral defeat, Chalmers used his first speech after being promoted to the senior portfolio to outline the opposition’s economic priorities.

While flagging a shake-up of its policies to take to the next election, Chalmers dismissed suggestions Labor should follow through on its pre-election pledge to conduct a review into Newstart, calling it an “unfortunate consequence” of the Coalition’s victory.

“That review won’t happen,” he said. “There are a lot of things we were proposing which had the potential to make a real difference to people’s lives, and when you think about what happened on election night, one of the things that does get you down is that we were not able to implement some of those policies and plans that we think would have made a real difference, particularly to vulnerable people in Australia.

“We have to accept the reality that we are three years from another election. I don’t think a review at the start of that from the opposition would necessarily shift the needle on Newstart.

“If people want to see a boost to Newstart, they have to convince the government.”

Chalmers also used the speech to outline Labor’s reasons for opposing the government’s $158bn tax cut package in its current form, saying the $95bn benefit to high income earners could not be justified.

The party is resisting pressure to support the full tax package, instead calling for the government to split the legislation, accelerate infrastructure spending and bring forward tax cuts already legislated.

It is also demanding more information from the government about the economic flow-on effect of tax cuts for higher income earners.

“My concern is that you get more bang for buck from tax relief from the people who are most likely to spend it,” he said. “The economic impact of tax cuts on the economy is different depending on how much disposable income you have and how much you are likely to spend the proceeds of a tax cut.

“If the government wanted our vote, they would give us the information we are seeking.”

After saying he believed the language about the “top end of town” during the election campaign was misplaced, Chalmers also said the party would be reviewing all of its policies following its defeat. But he said it was too early to say which pre-election pledges would be dumped.

“We won’t take the identical policy suite to the 2022 election that we took to the 2019 election,” he said. “We will obviously learn the lessons of what happened in the election campaign and why we got the result we did – it is the whole reason why we have been hitting the road and listening to people.

“We will come up with an agenda for the next election which isn’t the same as the last one which revisits our policies, revisits our language, frankly, but doesn’t revisit our values.”

As Labor revisits its policy platform, the government is remaining firm on its demand that its election tax cut pledge is passed in its entirety or not at all, with Mathias Cormann to put forward a motion to extend the Senate’s sitting hours next week, until the legislation passes.

But while Cormann may have his expectations of what is going to happen, Centre Alliance senator Rex Patrick said any extended sitting hours would be entirely at the will of the Senate, not the government.

“He certainly hasn’t sought any agreement with us on that and he would probably need it,” Patrick said. “I say that noting that anyone who is likely to vote against the tax package will vote against an hours extension and even those who may be for elements of the plan don’t see the urgency the government is placing on it – the parliament will sit again in a couple of weeks time and it won’t make that much difference.

“At this stage, we haven’t made a decision we’re not convinced of the merits of extending the sittings – Senator Cormann can put forward a proposition to the Senate, but it is a step too far to say that he will make the Senate do anything.”

Patrick and his Centre Alliance Senate colleague Stirling Griff control two votes in the Senate, where the government needs four crossbench votes to pass legislation Labor opposes.

With Cory Bernardi expected to vote with the government in most instances, One Nation and Centre Alliance, along with newly returned senator Jacqui Lambie become the crucial votes. Patrick said Centre Alliance had been in talks with Lambie to work together on legislation they share common ground on.

“Three really is the magic number,” Patrick said. “Stirling, myself and Jacqui can provide a pathway to the government to pass legislation, but it can also provide a block. For example, Centre Alliance and Jacqui both have difficulties with the government’s ‘ensuring integrity’ legislation in its current form, which would prevent it from going through the Senate.

“We are talking about working together when we have a common agreement. But we won’t be saying which way she intends on going on something and she won’t be talking about us.”