Bridget Phillipson has said the two child-benefit cap has had a “devastating impact”, as she signalled the government could soon lift it.

Asked whether this needed to happen now, the education secretary and deputy leadership candidate, told the BBC there was “a real urgency”.

The policy, introduced by the Conservatives, prevents households on universal or child tax credit from receiving payments for a third or subsequent child born after April 2017.

The government is widely expected to change the two-child limit in November’s Budget, with reports suggesting the Treasury is looking at different options to replace it, including a tapered system.

Asked if the chancellor was about to the lift the cap, Phillipson told the BBC’s Political Thinking with Nick Robinson podcast: “I’m leading the child poverty task force and I’ve been doing that work from government.

“But I’m clear about what needs to happen. I’m clear about what the evidence tells us. And I’m clear about what we need to do.”

She added: “There’s a real urgency about this because every year that passes, as children are born, as they move into that system, the numbers go up, child poverty rates increase. So we have to tackle it.”

The education secretary argued that children should not be “punished” for events beyond their control, for example if a parent loses their job and has to rely on benefits.

“This was a Tory policy that’s had a devastating impact on children and we’ll sort it,” she said.

Sir Keir Starmer has previously spoken of his desire to ditch the two-child cap when economic conditions allow, without specifying exact circumstances.

According to the Guardian newspaper, officials are considering whether there could be a tapered rate, so parents receive the most benefits for their first child and less for subsequent children.

Other options under consideration include limiting additional benefits to three or four children, the newspaper reported.

Asked whether the cap needed to be scrapped completely or if it could instead be amended, Phillipson told the BBC: “Through the work of the taskforce I see all the evidence, I look at the numbers, I look at the impact of different policies.

“This isn’t the only way we’ll take action, to be clear, because there are other steps we need to take, whether on skills, rights at work, much more besides, childcare. But I know what the evidence tells me.”

The Resolution Foundation think tank says axing the cap would cost an estimated £3.5bn and would lift 470,000 children out of poverty.

Campaigners have called for it to be abolished in full, arguing this would be the most cost-effective way to reduce child poverty.

Phillipson said tackling child poverty would be her “number one priority” if she was elected Labour’s next deputy leader, to replace Angela Rayner after her resignation last month.

“It really is personal to me. I know what it’s like to not grow up with very much,” she said.

Phillipson’s rival in the contest, her former cabinet colleague Lucy Powell, has also criticised the cap and said scrapping it would be the “single biggest policy we could do to address child poverty”.

Powell was sacked from her role as Commons leader in a reshuffle last month.

Phillipson rejected the idea that as a cabinet minister she would have less freedom to challenge the prime minister over government policy.

“What I’ll bring as deputy leader is the ability to unite our party and our movement,” she told the BBC.

“But alongside that I’ll be a strong voice at the cabinet table for members. So I’ll be in the room when those decisions are being made, able to push for the things that members want to see.”

Highlighting her record as education secretary, Phillipson said she had fought “tooth and nail” for policies like the expansion of free school meals.

She added that “there’s a limit to what you can do” from outside cabinet and “what I don’t think members want is for us to be airing our dirty linen in public”.

In her pitch to Labour members at a hustings on Wednesday, Powell said she would be a “full-time deputy” and “a strong independent voice”.

If elected, she pledged to have “difficult conversations” with the leadership, while refusing to “snipe from the sidelines”.

Although Phillipson gained more nominations to be deputy leader from her fellow MPs, published polling of party members has suggested Powell is the frontrunner in the contest.

However, Phillipson’s campaign have pointed to her greater number of nominations from the trade union movement.

Voting in a ballot of Labour members and affiliated supporters is open from 8 October to 23 October, with the result of the contest announced on 25 October.