Lynch-Staunton was appointed to the Senate on the recommendation of
Prime Minister Brian Mulroney on September 23, 1990. The following year, he was appointed Deputy Leader of the Government in the Senate, and he became
Leader of the Opposition in the Senate in December 1993 following the
Liberal victory in
that year's general election. From December 8, 2003, with the merger of the
Canadian Alliance and the
Progressive Conservative Party of Canada ratified by both parties, he served as
interim leader of the new
Conservative Party of Canada until the election of
Stephen Harper in March 2004. "Lynch-Staunton's high-road leadership of a Senate majority in opposition to an elected majority government in the Commons is a model for students of Parliament – and for future reference when history repeats itself". He remained Leader of the Opposition in the Senate until September 30, 2004, and retired from Parliament when he reached the mandatory retirement age of 75 on June 19, 2005. ==Retirement==