Conservative Senator Pamela Wallin has stepped down as chair of the Senate's national security and defence committee, citing personal reasons.
Ms. Wallin has also withdrawn as a member of that committee, as well as the foreign affairs committee and the subcommittee on veteran's affairs, the Senate communications office confirmed on Tuesday.
An assistant to Ms. Wallin said the senator asked for time away from her committee duties for "personal reasons." Mark Fisher, who works in her Ottawa office, said he did not know how much time Ms. Wallin expected to take away from the committees.
Sources in the Senate said they believe Ms. Wallin requested the leave because of an illness in her family. Her request was made last Wednesday and her positions on the national security and foreign affairs committees were filled by two other Conservative senators the following day.
Senator Salma Ataullahjan, from Toronto, will take Ms. Wallin's place on the foreign affairs committee, and Senator Dennis Patterson, who represents Nunavut, has been added to the national security committee.
The Senate is currently on a two-week break and will return to business in mid-April, when it is expected that members of the national security committee will elect a new chair.
Ms. Wallin was appointed to the Senate by Prime Minister Stephen Harper in 2009 and was elected as chair of the national security committee in 2010. She was re-elected as chair the following year, after the 2011 federal election. She is also a chancellor emeritus at the University of Guelph and an honorary colonel of the Royal Canadian Air Force.
Earlier this year, Ms. Wallin came under scrutiny for her travel expenses, which have since been referred to an external auditor for review. The expenses, which amounted to more than $321,000 between September, 2010, and the end of November, 2012, raised flags in part because only a small proportion of that money appeared to have been spent on trips between Ottawa and Saskatchewan, the province Ms. Wallin represents in the Senate.
Ms. Wallin said in February that many of her flights to Saskatchewan are not direct trips from Ottawa, which means they are listed as "other travel" on her expense claims.
Three other senators have also had their expense claims sent to an auditor. Liberal Senator Mac Harb, Conservative Senator Mike Duffy and independent Senator Patrick Brazeau are all being audited over the housing allowances they claim.
Senators are allowed to collect a stipend to cover their living expenses in the National Capital Region if their primary residence is located more than 100 kilometres away. Media reports have suggested the senators under review over housing expenses live primarily in Ottawa, raising questions about their entitlement to a stipend.
Government Senate Leader Marjory LeBreton has said the Senate will make the results of the audits public.