Labour leadership hopeful Andy Burnham will not accept an inflation-busting 10% pay rise planned for MPs.
The £7,000 increase, which will take MPs' salaries to £74,000, has been proposed by the Independent Parliamentary Standards Authority (Ipsa).
Mr Burnham said if the planned hike goes ahead he will turn it down at source or donate the money to "local groups".
The shadow health secretary said the proposed rise "cannot be justified".
Ipsa has launched a final review of the plans, declaring it could see no "material" reason to change them.
Unless a consultation produces "new and compelling evidence" by the end of the month, the move will be confirmed, with the rise backdated to May 8.
The increase was originally unveiled in 2013 to address complaints that MPs' pay has dropped behind that for other jobs.
Writing on Twitter, Leigh MP Mr Burnham said: "I have always been clear that 10% pay rise for MPs cannot be justified. I won't accept it. Will turn down at source or give to local groups."
David Cameron is set to receive the £7,000 pay rise despite previously branding the increase "unacceptable".
Downing Street has made clear the Prime Minister will not seek to block Ipsa's proposal - and he will personally get the extra money.
It means that, having declared last month that ministerial pay was being frozen for the duration of the parliament, Mr Cameron is in line for an effective 5% bump in his total remuneration, while Cabinet ministers' overall pay will increase by 5.2%.
Downing Street said that although Mr Cameron still opposed the backdated increase in MPs' pay, it was ultimately a matter for Ipsa to determine.
The premier's spokeswoman said he was focused on areas where he had the power to bring down the cost of politics, including proposals for boundary changes to reduce the number of MPs at Westminster.
The government element of salaries has been frozen until 2020, but unlike in the last parliament, the rise for MPs will not be offset by cutting ministerial pay.
Mr Cameron's total package will therefore rise by 5% this year, from £142,500 to £149,440.
Blocking the rise for rank-and-file MPs would have required a change in the law, and with a slim majority it was far from clear whether Mr Cameron would have been able to carry a vote in the Commons.
The document issued by Ipsa stressed that due to cuts in pensions and expenses - such as a ban on claiming for evening meals - the overall package of changes will not cost taxpayers "a penny more".
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article