Poirier joined the New Brunswick cabinet following the 2003 election as minister responsible for the Office of Human Resources and retained that post until a cabinet shuffle in early 2006 when she became Minister of Local Government and Minister responsible for Aboriginal Affairs.
She was re-elected in 2006 in which her party's government was defeated and went into opposition.
On January 29, 2010, she was appointed to fill a vacant New Brunswick seat in the Canadian Senate by Prime MinisterStephen Harper.[1] Her appointment became effective February 28, 2010.[2] Unlike the other four senators named on January 29, Poirier's appointment was delayed a month so that the government of New Brunswick would not have to call a by-election to replace her just months before the 2010 provincial election.[3]