Municipal politics, Part I

In 1982, Cullen was elected school board trustee with the Ottawa Board of Education representing the "Western Zone". In 1985, he was re-elected as a school board trustee representing Queensboro and Carleton Wards. During this time Cullen was also active in Kiwanis, serving as President of the Westboro Kiwanis Club in 1985-86.

In 1988 he ran for Ottawa City Council in the Richmond Ward but lost to incumbent Jacquelin Holzman. When Holzman vacated the seat to successfully run for mayor in the 1991 election, Cullen, then a community association president in the ward (Glabar Park Community Alliance), ran again and won the seat in a close three-way race.

As an Ottawa City Councillor he also served jointly on the Council of the Regional Municipality of Ottawa-Carleton. In 1994 Cullen was elected as the first Regional Councillor for Bay Ward, when provincial legislation created a directly elected Regional Council.

Provincial politics, Part I

In the 1985 provincial election, he ran as a Liberal candidate in the riding of Ottawa West but lost to Ontario Progressive Conservative Party incumbent Reuben Baetz, a cabinet minister, by about 3,000 votes.^[3] Cullen again sought the Liberal nomination to run in the Ottawa West riding in the 1987 election, but lost to local lawyer Bob Chiarelli. In 1996, Cullen supported Dalton McGuinty to lead the Ontario Liberal Party.^[4]

In 1997, Bob Chiarelli resigned from the Legislature to run for Chair of the Ottawa-Carleton Regional Municipality. In the subsequent Ottawa West by-election, Cullen ran for the Liberals and was easily elected as MPP.^[5] In May 1998, he gained national prominence as the only provincial legislator in the country to vote against the Calgary Declaration, as he opposed any document that didn't recognize the paramountcy of the Charter of Rights.^[6]

This vote made him unpopular within the Liberal Party. In the run-up to the 1999 provincial election, Cullen was challenged for the Liberal nomination in the new riding of Ottawa West—Nepean by Rick Chiarelli, a Nepean city councillor. In September 1998, Cullen lost the nomination battle to Chiarelli.^[7] On October 20, 1998 Cullen was expelled from the Liberal caucus and sat as an independent MPP.^[8] He joined the New Democratic Party a few weeks later, and subsequently won the NDP nomination in the riding.^[9]

In the 1999 Ontario general election, Cullen ran in the newly configured riding of Ottawa West—Nepean and placed third with 7,701 votes behind second place Chiarelli (16,419 votes). Progressive Conservative Garry Guzzo was elected with 22,834 votes.^[10]

Municipal politics, Part II

In 1999 Cullen became Executive Director of the Council on Aging, a United Way agency and lobby group for seniors. Cullen was elected to represent Bay Ward in newly amalgamated City of Ottawa in 2000, and was re-elected in 2003 and 2006, defeating high-profile right-wing challenger Terry Kilrea. During his tenure Cullen served as Chair of the City's Transit Committee (responsible for public transit service in Ottawa), and on the Board of Directors of Ottawa Community Housing (the City's social housing agency) and Hydro Ottawa.

On January 4, 2010, Cullen filed his nomination to run for mayor in Ottawa's 2010 municipal election.^[11] On August 31, Cullen dropped out of the race, citing low funds, the addition of another left wing candidate (Clive Doucet) and a desire to defeat Terry Kilrea in Bay Ward.^[12] On October 25, 2010, Cullen lost in his bid for re-election in Bay Ward to challenger Mark Taylor. Cullen cited his late entry into the race in Bay Ward as the reason for his loss.^[13]

Provincial politics, Part II

In January 2013, Cullen sought the Ontario NDP nomination in the riding of Ottawa Centre for the 41st Ontario general election, but was defeated by Ottawa-Carleton District School Board Trustee Jennifer McKenzie.^[14] Cullen subsequently won the Ontario NDP nomination in the riding of Ottawa West—Nepean^[15] but was defeated on June 12, 2014, by the Liberal candidate Bob Chiarelli.

Municipal politics, Part III

In June 2014, Cullen registered to run in Bay Ward (his former municipal ward) in the City of Ottawa, against incumbent Mark Taylor. Cullen received media attention during the election upon the release of his report on the 2010 Ottawa municipal election finances (similar to previous reports Cullen had written following the 2003 and 2006 municipal elections), where he made a case for banning corporate and union campaign contributions.^[16]

On October 27, 2014 (election day) Cullen lost to incumbent Mark Taylor in a closely fought campaign by 474 votes (Taylor: 5,750; Cullen 5,276; 4 other candidates 1,234).^[17]