Question: The 17th Premier of Nova Scotia and leader of the federal Progressive Conservative Party of Canada Robert Stanfield fought a few times and lost in general elections against which politician who is currently one of the longest-serving Prime Minister in Canadian history?
Context: Peter Gordon MacKay {'1': ", '2': ", '3': ", '4': "} (born September 27, 1965) is a lawyer and politician from Nova Scotia, Canada.  He was a Member of Parliament from 1997 to 2015 and has served as Minister of Justice and Attorney General (2013–2015), Minister of National Defence (2007–2013), and Minister of Foreign Affairs (2006–2007) in the Cabinet of Canada under Prime Minister Stephen Harper.  MacKay was the final leader of the Progressive Conservative Party of Canada (PC Party), and he agreed to merge the party with Stephen Harper's Canadian Alliance in 2003, forming the Conservative Party of Canada. Marjory LeBreton, PC (born July 4, 1940) is a former Leader of the Government in the Canadian Senate, a cabinet-rank position; and past national chair of Mothers Against Drunk Driving in Canada.  She worked with four leaders of the Progressive Conservative Party of Canada - John Diefenbaker, Robert Stanfield, Joe Clark and Brian Mulroney - from 1962 to 1993 before being appointed to the Senate on the advice of Mulroney.  She sat as a Progressive Conservative Senator from her appointment until moving with most of her caucus colleagues to the new Conservative Party of Canada in 2004, of which she was soon elected to Chief Whip.  She served as an advisor to then opposition leader Stephen Harper during the 2006 election, which the Conservative Party won.  After the election, she was named to the cabinet position Leader of the Government in the Senate.  On July 4, 2013, LeBreton announced she would not continue in the position as of the next cabinet shuffle, which occurred later that summer.  She retired from the Senate upon reaching her 75th birthday on July 4, 2015. Darrell Elvin Dexter (born September 10, 1957) is a Canadian lawyer, journalist and former naval officer who served as the 27th Premier of the Canadian province of Nova Scotia from 2009 to 2013.  A member of the Nova Scotia New Democratic Party, he served as party leader from 2001 to 2013.  He became Premier in 2009 after his party defeated the governing Progressive Conservative Party, leading the first NDP government in Atlantic Canada and the second east of Manitoba.  His government was defeated in the 2013 election, becoming the first Nova Scotia government in 131 years to be denied a second mandate; Dexter himself was defeated in his constituency by 21 votes. Joseph Philippe Pierre Yves Elliott Trudeau, ( ; ] ; October 18, 1919 – September 28, 2000), often referred to by the initials PET, was a Canadian statesman who served as the 15th Prime Minister of Canada (1968–1979 and 1980–1984).  He is the 3rd longest-serving Prime Minister in Canadian history (behind William Lyon Mackenzie King and John A. Macdonald), having served for 15 years, 164 days. Arthur William (Bill) Cox, Q.C., LL.D.  (May 13, 1921 – October 8, 2008) was a Canadian lawyer, practising in Halifax, Nova Scotia.  He served overseas during World War II.  On his return to Canada, he became an active member of the legal profession, serving as president of the Nova Scotia Barristers' Society (1971-1972), the Federation of Law Societies of Canada (1975-1976) and the Canadian Bar Association.  He was also active politically, with both the Progressive Conservative Party of Canada and the Progressive Conservative Party of Nova Scotia. Blue Tories, also known as small 'c' conservatives, are, in Canadian politics, members of the former federal Progressive Conservative Party of Canada, current Conservative Party of Canada and provincial Progressive Conservative parties who are more economically right wing.  Prior to the 1960s, these Conservatives were most identified with the Montreal and Toronto commercial elite who took positions of influence within the Progressive Conservative Party.  Since the mid-1970s, they have been heavily influenced by the libertarian movement and the more individualist nature of American conservatism.  Blue Tories tend to favour libertarian policies such as devolution of federal power to the provincial governments, a reduced role for government in the economy, reduction of taxation and similar mainstream market liberal ideals.  The term Blue Tory does not refer to social conservatism. Robert Lorne Stanfield, PC, QC (April 11, 1914 – December 16, 2003) was the 17th Premier of Nova Scotia and leader of the federal Progressive Conservative Party of Canada.  He was born into an affluent Nova Scotia clothing manufacturing and political family in 1914.  He graduated from Dalhousie University and Harvard Law School in the 1930s.  Stanfield became the leader of the Nova Scotia Progressive Conservative Party in 1948, and after a rebuilding period, led the party to government in 1956.  As premier, he won three straight elections.  His government was credited with modernizing the way the province delivered education and medical services.  In 1967, he resigned as premier and became the leader of the federal Progressive Conservative Party.  He was the leader of the "Her Majesty's Loyal Opposition" and fought three general elections, losing each time to the Liberals under Pierre Trudeau.  He resigned as leader in 1976 and from public office in 1979.  In retirement, he lived mostly in Ottawa, and died there in 2003 from complications due to pneumonia.  He is sometimes referred to as "the best prime minister Canada never had".  As one of Canada's most distinguished and respected statesmen, he was one of several people granted the style "The Right Honourable" who were not so entitled by virtue of an office held. Jean James Charest, PC (born John James Charest; ] ; born June 24, 1958) is a Quebec politician.  He was the 29th Premier of Quebec, from 2003 to 2012; the Deputy Prime Minister of Canada from June 25, 1993, until November 4, 1993; the leader of the federal Progressive Conservative Party of Canada from 1993 to 1998; and the leader of the Quebec Liberal Party from 1998 to 2012.  He became Premier after winning the 2003 election; after he lost the 2012 election he announced that he would be resigning as Quebec Liberal Leader and leaving politics.  Charest sits as an advisor to Canada's Ecofiscal Commission. Halifax Stanfield International Airport (IATA: YHZ, ICAO: CYHZ) is a Canadian airport located in Enfield, Nova Scotia, an area of Halifax, Nova Scotia.  It serves Halifax, mainland Nova Scotia and adjacent areas in the neighbouring Maritime provinces.  The airport is named in honour of Robert Stanfield, the 17th Premier of Nova Scotia and leader of the federal Progressive Conservative Party of Canada. George Isaac Smith (April 6, 1909 – December 19, 1982), usually referred to as G.I. Smith, was a Canadian lawyer and politician who served as the 18th Premier of Nova Scotia from 1967 to 1970.  He was a Canadian senator from 1975 until his death.  G.I. Smith is noted for having recruited Robert Stanfield to help rebuild the Progressive Conservatives in Nova Scotia.
Answer: Pierre Trudeau