Rebecca Long-Bailey has vowed to abolish the House of Lords if she were to be elected Prime Minister.
The Labour leadership hopeful said she would unveil a radical package of constitutional measures if she succeeded Jeremy Corbyn.
Speaking to Sky News’s Sophy Ridge on Sunday programme, the shadow business secretary said: “I do want to abolish the House of Lords and we’ll be rolling out as my campaign progresses how we intend to really shake up that constitutional package.”
She added: “There would need to be checks and balances in place, but to have a set of completely unelected people doing that I don’t think is right.”
Ms Long-Bailey has been seen as the candidate most likely to continue Jeremy Corbyn’s hard left leadership of the opposition party.
On Saturday she received support from parts of the Momentum activist group, which campaigns for Mr Corbyn.
Ms Long-Bailey also indicated that, were she to be in charge of the country, she would allow another referendum on Scottish independence.
She said: “I’m fully committed to the union and I don’t think that should be shaken in any way, but ultimately the people of Scotland need to make the case.
“They’ve got their own Parliament to determine whether they want to push that and that will be for me as a prime minister to review and to look at.
“I wouldn’t want to inhibit the democracy of people because that’s one of the most fundamental pillars that we’re proud of in this country.”
Ms Long-Bailey said she would work “very hard and very robustly” to tackle anti-Semitism in the party and she was unhappy at the way the issue had been dealt with.
“I wasn’t happy with the way our process was being run, I’ll be honest, I don’t think we were dealing with complaints quickly enough and I think that’s quite clear, I’ve been quite vocal about that,” she said.
“I spoke to Jeremy about it, I spoke to the various members of the team, I spoke to various members of the NEC (national executive committee) about that.”
Asked if Mr Corbyn bore personal responsibility, she said: “He does and he’s apologised.
“I think any Labour politician that leads the Labour Party should apologise again for what has happened because it has been unacceptable.”