The MP in charge of the Commons sleaze watchdog stood down tonight pending an inquiry into his second home allowance claims.
Conservative David Curry is facing allegations that he claimed almost £30,000 towards the cost of a property that his wife does not allow him to use.
According to the Daily Telegraph, she demanded he did not use the cottage in Yorkshire as a condition of their reconciliation after she discovered he was having an affair.
After being challenged about the claims, the MP for Skipton and Ripon has referred his case to John Lyon, the Parliamentary Commissioner for Standards who investigates alleged expenses abuse.
Mr Lyon's reports are passed to the Standards and Privileges Committee - to which Mr Curry was appointed as chairman last month - for its recommendations for punishment.
Mr Curry said tonight: "I used the cottage to carry out my duties as a constituency MP and am content with my arrangements.
"However, given the particular responsibilities of the chairman of the Committee of Standards and Privileges, I shall refer my case to the Commissioner on Parliamentary Standards John Lyon and will stand down from the chairmanship during the course of his inquiries."
Mr Curry, a former Tory minister, designated the cottage as his second base in 2005 after moving back into his family home in Essex.
Since then, he has claimed £28,078 in expenses towards its upkeep.
That included the installation of a new damp course, the hiring of a local consultant to oversee the work, roof repairs and redecorating.
He also claimed about £250 a month towards the mortgage until it was paid off in 2007.
The Telegraph reported that Mr Curry rarely stayed in his constituency and, when he did, usually stayed at the local £40-a-night Travelodge.
He told the newspaper he had used the cottage less than he would have liked in previous years, but put the reasons down to maintenance work and his father's illness.
"The cottage has been my constituency home since 1987. In the (past four years) I have used it less intensively before because I preferred, if possible, to get back to my family home," he said.
"In addition, between November 30, 2007 and June 27, 2008, the cottage was uninhabitable because of works being carried out (under warranty) to replace a failed damp-proof course.
"My father was diagnosed with a terminal cancer in 2006 (he died in June 2008) and I tried to stay with him on the northern edge of Leeds whenever possible since he lived there alone.
"I am currently dealing with the consequences of a major leak at the cottage - under insurance."
He added that he stayed at the Skipton Travelodge because he represented a large constituency and it was sometimes more convenient.
Mr Curry has already announced he is stepping down from Parliament at the next general election.
A Conservative Party spokesman said: "We can confirm that David Curry has said that he will refer himself to the Commissioner on Parliamentary Standards and stand aside as chairman of the Committee on Standards and Privileges for the duration of the inquiry."