He is survived by his wife of over 30 years, Diane Finley, a senior federal Conservative cabinet minister, his daughter Siobhan by a previous marriage, and three grandchildren.
“Doug fought a hard and very public battle with cancer. His death is a loss to our family, our friends — and to the entire country," the Human Resources Minister said in a written statement on Saturday.
“Although further details will soon be announced, I do ask that our family have some privacy as we prepare to formally bid farewell to a great man."
Born in Exeter, UK on July 25, 1946, Finley's parents quickly moved him to Scotland to ensure that he was “raised properly," said Frank Parker, Finley's policy advisor, in a public statement.
Finley, a political warrior, was best known as Prime Minister Stephen Harper's "pitbull."
His reputation was built on fierce loyalty to the party and hard work. As national campaign director, Finley was credited with leading the Conservative Party to victory first in 2006, and again in 2008.
Condolences from the PM, opposition
Harper expressed his condolences in a statement, saying "a great Canadian has been taken from us, before his time."
“It was with great sadness that Laureen and I learned of the death of Senator Doug Finley. Our government has lost a trusted adviser and strategist. Canada has lost a fine public servant. I have lost a dear and valued friend," Harper said.
“When he learned he had cancer, Senator Finley faced this vicious opponent like the fighter he was. He continued to participate in Senate debates almost to the end, and shared information about his diagnosis and treatment with the public," Harper said.
Harper appointed Finley, in 2003, as director of political operations of the Canadian Alliance. He was later appointed director of political operations of the newly-formed Conservative Party of Canada, and was considered the engineer behind the 2004 Conservative breakthrough in Ontario.
“Senator Doug Finley’s passing is a significant loss to the conservative movement in Canada,” said John Walsh, president of the Conservative Party of Canada, in a written statement.
Walsh recalled "his tireless work in the building of this party, his deep commitment to the Senate of Canada, and his passion for his home of Scotland."
"Doug helped turn the party into the disciplined organization it is today. He was also proud of his service to Canada by helping to give it an honest, accountable, and affordable Government," said Jenni Byrne, director of political operations for the Conservative Party of Canada, in a written statement.
Opposition leader Tom Mulcair, in a statement posted on the party's web site, offfered his condolences on behalf of the New Democrats saying Finley's death "will be mourned beyond party lines."
Liberal leader Justin Trudeau also expressed his condolences on Twitter saying, "saddened to learn of @SenatorFinley's passing. Sophie and I send our deepest condolences to Diane and her family."
Former interim Liberal leader Bob Rae also took to Twitter saying that Finley was a "tough opponent whose gruff exterior belied his big heart."
Working while fighting cancer
In August 2009, Finley was appointed to the Senate to represent Ontario South Coast.
After Finley was diagnosed with terminal cancer, the Senator continued to show up for work, even as he underwent chemotherapy treatment every two weeks.
In an interview with CBC Radio's The Current in December 2012, Finley said it was "manageable" and that he'd come to "accept the limitations."
"The Senate is something that I can look forward to. I get up in the morning, it causes me to think, to plan, to strategize… to meet people. So it's really important for me personally."
Finley was seen in the Senate as recently as last Tuesday, when he was present for the vote to send Bill C-377, An Act to amend the Income Tax Act, to committee and spoke on Bill C-383, the Transboundary Waters Protection Act.
Marjory Lebreton, the leader of the government in the Senate, said in a written statement, that was proof of his "tenacity."
"He never gave up, he displayed great courage, never complained and fought it to the end," adding that "the description of a 'fighting Scot' describes him perfectly."
Finley's political career was not without controversy.
In 2011, Elections Canada charged Finley and Conservative Senator Irving Gerstein, a Conservative fundraiser, for allegedly breaking election laws during the 2006 federal election.
The charges were later dropped as part of a plea deal with the Conservative Party in what became known as the "in-and-out" financial scheme.
"My legacy will be my family," Finley told CBC News.Suggest a correction