Sir Keir Starmer has said he would scrap the resignation honours list if he became prime minister as he described the tradition as "hard to justify".
The Labour leader was speaking in the wake of a row over Boris Johnson's list, which saw him reward a number of his closest political allies. An initial draft of the list included eight names whose peerages were subsequently blocked by the House of Lords appointments committee (Holac).
The Labour leader told BBC Radio 4's Today programme: "Tony Blair didn't have a resignation list. It's very hard to justify. If it was reserved for, you know, people who had given incredible service, perhaps picking out people who have, you know, been involved in the development of the vaccine or some other incredible public service.
"But it's very hard to see how it's justified. There are other avenues for that, and I think it's easier to be clean about this and simply say 'no, I wouldn't do it'. Tony Blair didn't do it and I wouldn't do it."
Sir Keir also said Rishi Sunak should have put Mr Johnson's honours list "to one side" and waited for the recommendations of the privileges committee report into partygate.
It comes as MPs are set to debate and vote on the findings of the committee, which would have seen Mr Johnson - who quit after he learned of the recommendations - face a 90-day ban from the House of Commons for "repeated contempts" of Parliament.
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Rishi Sunak must "show leadership" and support the privileges committee's report into Boris Johnson, Sir Keir Starmer has said.
MPs are set to debate and vote on the findings of the committee, which would have seen the former prime minister face a 90-day ban from the House of Commons for "repeated contempts" of Parliament, on Monday evening.
It was widely reported overnight that Mr Sunak may join other ministers in missing the vote as he welcomes his Swedish counterpart to Downing Street.
Speaking in Edinburgh ahead of a speech setting out Labour's green agenda, Sir Keir told BBC Breakfast: "I want to see the Prime Minister there when I arrive back in Parliament because he has to show leadership.
"What his predecessor got up to was unacceptable. If the Prime Minister wants to lead he has to come in and vote in this debate this afternoon to show where he stands on this issue."
In an interview with Good Morning Britain, Mr Sunak declined to say whether he would be there for the vote and insisted he did not want to "influence" Tory colleagues, adding: "It will be up to each and every individual MP to make a decision of what they want to do when the time comes."
Sir Keir Starmer has said a Labour government would force councils to identify suitable sites for new wind farms.
Speaking to BBC Radio 4's Today programme, the Leader of the Opposition insisted he wanted to work towards a "position of consensus", but there must also be a "mechanism where we can move forward".
"Because otherwise you get to a situation where everybody says there ought to be more renewables and onshore wind but I just don't want it near me. So we have to have a situation where we can resolve that.
"And one of the things that we're setting out today is, therefore, amendments to planning regulations to ensure that not only do we lift the ban on onshore wind, but that we work with local communities, but in the end require local authorities to identify land that they think is suitable."
Sir Keir added: "There has to come a point where if we're going to move forward, that we don't have simple individual vetos across the whole of the country... What we're setting out today is a plan for clean power by 2030. The drivers of that are to make sure that we get cheaper bills on (sic) the long-term, not the short-term."
Sir Keir Starmer said he would not have his own resignation honours list, saying it would be "very hard to justify".
The Labour leader told BBC Radio 4's Today programme: "Tony Blair didn't have a resignation list. It's very hard to justify. If it was reserved for, you know, people who had given incredible service, perhaps picking out people who have, you know, been involved in the development of the vaccine or some other incredible public service.
"But it's very hard to see how it's justified. There are other avenues for that, and I think it's easier to be clean about this and simply say 'no, I wouldn't do it'. Tony Blair didn't do it and I wouldn't do it."
Rishi Sunak appeared to rule out further state help for mortgage holders, insisting the focus must be on cutting inflation.
The Prime Minister was asked by Good Morning Britain whether he would launch a scheme similar to programmes which have offered direct support for Britons with their energy bills.
"I know the anxiety people are going to have about mortgage rates," Mr Sunak said. "That's why the first priority I set out at the beginning of the year was to halve inflation, because that's the best and most important way that we can keep costs and interest rates down for people.
"We've got a clear plan to do that. It is delivering, we need to stick to the plan. There is also support available for people, we have the mortgage guarantee scheme for first-time buyers, and we have the support for mortgage interest scheme, which is there to help people as well."
Rishi Sunak has refused to say whether he will endorse the privileges committee's report into Boris Johnson.
In an interview with Good Morning Britain, Mr Sunak said the cross-party group of MPs would have "done their work thoroughly" but it was 'a matter for the House, not for the Government".
Asked if this meant he would miss the vote, the Prime Minister replied: "So, each and every individual colleague will make up their mind when the time comes. This is a matter for the House rather than the Government. It's an important distinction and that is why I wouldn't want to influence anyone in advance of that vote."
Pressed on whether he needed to 'set an example", Mr Sunak said: "As I said this is a matter for the House. It's not a government matter.
"It will be up to each and every individual MP to make a decision of what they want to do when the time comes, it's important the government doesn't get involved in that because it is a matter for parliament and members as individuals, not as members of government."
Dominic Penna here, The Telegraph's Political Reporter, guiding you through what is shaping up to be a dramatic day in Westminster.
MPs are expected to vote on the privileges committee report into Boris Johnson which would have seen the former prime minister - who quit Parliament ahead of its publication - banned from the Commons for 90 days for "repeated contempts" with his partygate denials.
Rishi Sunak declined to say this morning whether he would take part in the debate or cast a vote on the report, with several ministers including Michael Gove, the Housing Secretary, planning to abstain.
Meanwhile Sir Keir Starmer, the Labour leader, is in Edinburgh for a speech just after 10am in which he will be setting out his party's stall on green energy.