Michael Fortier, who was appointed to cabinet in 2006 despite not being elected to office, resigned from the Senate on Monday to run as a Conservative candidate in Quebec in the upcoming federal election.
Fortier, whose appointment as federal public works minister by Prime Minister Stephen Harper sparked controversy following the 2006 election, has since passed on several opportunities to run in byelections.
The lawyer and financier previously said he didn't run for office in 2006 because he "didn't want to run."
Fortier made headlines earlier this summer when he dismissed a senior member of his staff because the man had a romantic relationship with Julie Couillard last year as a company she represented was bidding on a big government contract.
Couillard is the former girlfriend of Maxime Bernier, who resigned from the foreign affairs portfolio in May following Couillard's revelations he had left confidential government documents at her residence.