Dewar was first elected to the House of Commons in the 2006 federal election. He served as the Official Opposition Critic for Foreign Affairs, until he left the post in October 2011 to run for the leadership of the NDP. Dewar lost his seat during the 2015 federal election which saw the NDP lose all of its seats in Eastern Ontario. Before entering politics he worked as a teacher and was an elected representative of the Ottawa-Carleton Elementary Teachers' Federation.
Dewar was born in Ottawa, Ontario on January 25, 1963 to parents Ken Dewar and former Ottawa mayor and New Democratic Member of Parliament, Marion Dewar. When he was in grade three, Dewar was diagnosed with dyslexia, after his teacher noticed that he was struggling to read and write. He earned a Bachelor of Arts degree from Carleton University in political science and economics in 1985.
Not long after he completed his Bachelor of Arts, Dewar embarked on a five-month trip to Nicaragua, where he volunteered as an aid worker. Following his return to Ottawa, he began working as constituency assistant to Ontario Minister of Health and NDP Member of Provincial Parliament for Ottawa Centre, Evelyn Gigantes. Dewar served in this position from 1990 to 1995. It was during this time that he met his wife, Julia Sneyd. They later had two children together: Nathaniel and Jordan.
Dewar attained a Bachelor of Education degree from Queen's University in 1994. He went on to work as an elementary school teacher at D. Roy Kennedy Public School and as an English teacher at Hopewell Avenue Public School. His work with students with special needs led Queen's University to award him the A. Lorne Cassidy Award.
While working at the schools, Dewar became involved with his union, the Ottawa-Carleton Elementary Teachers' Federation (OCETF; a local of the Elementary Teachers' Federation of Ontario). After having served as a member of OCETF Executive and as the chair of their political action committee, he was elected Second Vice-President in 2001 and First Vice-President in 2004. During his time with the union, Dewar played a major role in reviving the OCETF's political action committee and in establishing the Elementary Teachers' Federation of Ontario's Humanity Fund, which provides financial support to various charities doing work in developing countries, such as the Stephen Lewis Foundation. He took a leave of absence from his position with the OCETF in 2006 to run in that year's federal election.
In 2002, Dewar organized a Community Forum on Public Education. He has also been actively involved with the Coalition for a Healthy Ottawa, the Partnership for a Pesticide Bylaw, the Old Ottawa East Community Association, and Fair Vote Canada, and he has served on the board of directors of the Ottawa Community Immigrant Services Organization.
Dewar was raised in a Catholic household, but he takes issue with the church's positions on same-sex marriage, birth control, and women's rights. He has been active with First United Church since 2001.
Dewar ran for the New Democratic nomination in Ottawa Centre for the 2004 federal election. Several weeks after Dewar started his campaign, former NDP leader Ed Broadbent came out of retirement to also seek the nomination. After Broadbent won, Dewar went on to volunteer for Broadbent's successful campaign in the general election, playing a major role in organizing the NDP election day effort.
In order to care for his ailing wife, Broadbent decided not to seek re-election. Dewar won the proceeding nomination contest on June 22, 2005 on the first ballot, defeating NDP caucus Research and Communications Director Jamey Heath, who was the riding's candidate in the 1997 election, lawyer and film producer Tiffani Murray, and Ottawa Citizen automotive columnist Shannon Lee Mannion.
Dewar won the 2006 election and became an MP.
Dewar was acclaimed on February 12, 2007 as the New Democrats' candidate for the 2008 federal election. He was re-elected on October 14, 2008, by a substantial margin over his closest challenger, Penny Collenette of the Liberal Party.
Since February 5, 2009, Dewar has served as the Chair of the All-Party Parliamentary Group for the Prevention of Genocide and Other Crimes Against Humanity.
In April 2009, Dewar reintroduced legislation to protect Gatineau Park. If passed the act would have provided legislated boundaries for the park, prevented removal of land from the park, created a mechanism for expanding the park, and mandated the National Capital Commission to acquire private lands in the park through a right of first refusal process. However, he was later criticized in the media for having abandoned his commitments on the park, for supporting the Conservative government’s legislation, and for not attending the committee studying that legislation.
Dewar was re-elected in the 2011 federal election, winning 52% of the popular vote. The NDP formed the Official Opposition following the election and Dewar was named the Critic for Foreign Affairs. While acting as foreign affairs critic, Dewar took a position in favour of the UN Arms Trade Treaty not exempting weapons designed for sport or hunting, an exemption that the Canadian government was proposing at international talks. Dewar explained in media interviews that in his view it was important that the UN treaty cover all small arms because of the effects that they have had in conflicts in Africa.
Dewar criticized the government's decision to close its embassy in Iran, saying it was 'bad diplomacy'
Dewar was one of thirteen Canadians banned from traveling to Russia under retaliatory sanctions imposed by Russian President Vladimir Putin in March 2014.
Following the death of Jack Layton in August 2011, Dewar was seen as a potential candidate to succeed him as leader. On October 2, 2011, Dewar announced his candidacy for the leadership of the New Democratic Party. Dewar was considered to be among the leading candidates in the seven person racing, however his lack of fluency in French was seen as a major obstacle. While internal polling released by his campaign showed he was among the top three candidates and had strong growth potential, on election day he finished fifth out of seven candidates on the first ballot with 7.5% of the vote. Following the first ballot he withdrew his candidacy and did not endorse any other candidates.
Source: Elections Canada