Senior Tory backbencher Derek Conway said on Wednesday he would not fight the next general election after coming under intense fire for paying his son £45,000 ($89,000) from public funds.

His announcement came as the head of the parliamentary standards committee mooted a ban on MPs employing members of their families.

Mr Conway’s decision to step down as the Conservative MP for Old Bexley and Sidcup came less than 24 hours after David Cameron removed the party whip, in effect casting the senior backbencher out of the Tory fold.

Mr Cameron was criticised for initially supporting Mr Conway in the face of a finding by a parliamentary standards watchdog that the MP had misused public funds when employing Frederick, his younger son, as a research assistant.

Wednesday’s announcement is unlikely to mark the end of Mr Conway’s woes. MPs will vote on Friday on whether to suspend him for 10 days and require him to pay back £13,161 of the public money paid to his son.

Mr Conway faces a possible inquiry into complaints about his employment of his other son, Henry, as well as a potential police investigation. The disgraced backbencher’s decision to fall on his sword will come as a relief to his party leader.

Mr Conway said on Wednesday he did “not wish my personal circumstances to be a distraction in any way” for Mr Cameron.

His decision to leave parliament will mitigate the risk of the Tories being tainted by “sleaze”, reducing their ability to extract political advantage from the police inquiries into donations to Labour.

The MP’s misdemeanours could have wider repercussions for the way parliament as a whole operates. Mr Conway’s payment of a salary and bonuses to Frederick in return for no apparent work, while the latter was a full-time student, has thrown a harsh media spotlight on the lax controls governing the system of allowances.

MPs can each spend up to £87,276 – soon increasing to £96,640 – a year on employing researchers, secretaries and assistants. About 40 MPs have wives or children working in their Westminster offices, while others employ relatives in their constituency.

Experts are questioning whether such nepotism can be allowed to continue, particularly given the lack of full disclosure of MPs’ staff and the payments to them.

Sir Christopher Kelly, chair of the committee on standards in public life, on Wednesday characterised the Conway case as “undoubtedly a very serious breach of parliamentary rules” that “further undermines public trust in our politicians”.

“I understand why there are calls for rules to ban employing members of their families ... There are international precedents for this and it could be the right thing to do,” Sir Christopher said.

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