The Ontario Green Party did not originally have a formal leadership structure, and was run in a very decentralized manner. De Jong and others opposed this approach, and successfully campaigned for a formal leadership contest in 1993. De Jong himself entered this contest, and defeated Jim Harris, who later became leader of the Green Party of Canada. De Jong supported Harris's leadership of the federal party until Harris stepped down in 2006, at which time de Jong supported David Chernushenko's leadership bid. He was challenged for the leadership of the Ontario Green Party by Judy Greenwood-Speers in 2001.
Like Harris, de Jong is an eco-capitalist. He defines his political philosophy as "socially progressive, fiscally conservative, and environmentally aware". He has long supported conservative economic policies, including a gradual shift from the taxation of incomes to the taxation of natural resources. Recently, he has also spoken against extensive government subsidies and funding for crown corporations. At the October 2005 Green Party of Ontario Annual General Meeting, de Jong narrowly avoided a "leadership review" when 67% of voting members voted against it. The GPO constitution requires that a leadership review be held bi-annually; If more than one-third of voting members had opted for a review, a leadership race would have been held in 2006. At the 2007 AGM, de Jong survived the next scheduled review, this time with approximately 71% support from party members. This followed what was considered the strongest election performance by the GPO to date. Speaking at the Green Party of Ontario AGM in May 2009, de Jong announced that he will not be running for re-election as leader of the party. In the September 14, 2006, Parkdale—High Park by-election, de Jong received 6.2 percent of the vote. On November 7, 2006, he was nominated as the GPO candidate in the riding of Davenport for the 2007 Ontario general election. In that election, de Jong captured 10.26 percent of the vote, his best showing as a member of the Green Party. De Jong was a candidate for Ward 18 in Toronto's 2010 municipal election. As of December 2014, de Jong was living in Faro, Yukon and was the Green Party of Canada candidate in the Yukon riding in the 2015 federal election, placing a distant fourth. De Jong was elected leader of the Yukon Green Party in September 2016.
Election campaigns
De Jong has campaigned for federal and provincial office several times. His best showing was in the provincial election of 2003, when he ran against sitting PremierErnie Eves and finished third, ahead of the New Democratic Party candidate. On all other occasions, de Jong has finished well behind candidates of the major parties. During the 1995 provincial campaign, de Jong cycled on a "leader's tour" from Ottawa to Sault Ste. Marie, Windsor and Niagara Falls before returning northward to Ottawa. Subsequently, he was involved in creating constituency contact lists throughout the province. His electoral record is as follows: 1991 Ottawa municipal election 2010 Toronto municipal election, Ward 18: Davenport !align="left" colspan=3|Total !align="right"| 661 !align="right"| 100.0% !align="right"|-
