Labour has offered to co-operate with the Government in rushing through emergency legislation to stop prime ministers handing out honours on leaving office.
The offer came amid controversy over David Cameron's resignation honours list, which saw awards for a string of political allies, Tory donors and Downing Street staff.
The chairman of the Committee on Standards in Public Life, Lord Bew, told The Sunday Telegraph that the list of 59 Cameron nominations for peerages and gongs "has to be the last one, given the public outcry".
Labour deputy leader Tom Watson urged Prime Minister Theresa May to ensure that this was the case by legislating to end the practice. And he said she should lead by example by announcing now that she will not making nominations when she leaves office.
In a letter to Mrs May, Mr Watson said that her predecessor's list had "undermined the credibility of the honours system" and was an embarrassment to existing members of the House of Lords, as well as being "disheartening" to people who had received honours for service to the country.
Amid press reports that Mrs May is seeking a way to draw a line under the row, he said: "I would be grateful if you could outline the timetable for removing the discretionary powers of prime ministers to award resignation honours to their acquaintances and friends. How will the power be removed? It seems to me it may require primary legislation.
"Rest assured Labour will co-operate with any emergency legislation you would like to bring forward when the Commons sits next month. In light of the seriousness of the matter, please also give a guarantee that, in the event of your early departure from office, you will not use the discretionary power yourself. It's important that you lead by example and are seen to be doing so."
Mr Watson also called for a leak inquiry after a list of nominations was obtained by The Sunday Times ahead of their official publication.