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 upcoming October 2007 general election. In the Ontario provincial election on October 10, de Jong captured 10.26 percent of the vote, his best showing as a member of the Green Party. De Jong has also campaigned for federal office as a member of the Green Party of Canada.