Van Ojik comes from the Political Party of Radicals, one of the four parties that merged to form GroenLinks in 1989. Van Ojik had been member of the PPR since 1973. Between 1972 and 1980 Van Ojik studied economics at the Free University. He specialized in development economics. Between 1978 and 1981, he served on the board for radical education. As a conscientious objector, Van Ojik did his alternative service at the development organization NIO. After that he worked for the scientific bureau of the PPR until 1983. Here he wrote a book on basic income. In 1986 he co-authored the PPR's election program. Between 1985 and 1988, he was editor-in-chief of the PPR party paper. Between 1988 and 1990 he was party chair of the PPR. As chair of the PPR, he was involved in the negotiations over the formation of GroenLinks, a new political party formed by the merger of the Pacifist Socialist Party, Communist Party of Netherlands, and Evangelical People's Party. Van Ojik had always favoured cooperation between the four parties, but the PPR party board soon wanted to abandon negotiations. Van Ojik had to defend this, although he did not support it. The formal PPR delegation was replaced by an informal delegation by former party chair Wim de Boer. In 1989 the talks led to the formation of a new party. Van Ojik became a member of the first party board. In addition to these activities, Van Ojik freelance journalist and advisor on the subject of development cooperation. Between 1990 and 1993 Van Ojik worked for Oxfam NOVIB.
GroenLinks
Between 1993 and 1994, Van Ojik was member of the House of Representatives for GroenLinks. He replaced PPR member Ria Beckers. He spoke on agriculture, development cooperation and science. He prepared an initiative to limit the use of wood from the tropics. It was finally proposed in 1994 by Marijke Vos. At the 1994 election Van Ojik was put on the seventh place of the GroenLinks list, the same place he had in 1989. GroenLinks only won five seats. He also co-authored the GroenLinks election program. In 1997 Van Ojik again co-authored GroenLinks election program for the 1998 election. For GroenLinks, Van Ojik chaired a committee which evaluated the municipal elections, parliamentary and provincial, all of which GroenLinks had lost. Then he became chair of the committee which oversaw a debate within GroenLinks on the party's principles, strategy and organizations. This led to a new manifesto of principles in 2008 of which Van Ojik is one of the co-authors. After national elections on 12 September 2012 the size of the representation of the GroenLinks party within the House of Representatives was reduced from 10 seats to 4 seats. On 8 October 2012 Van Ojik became leader in the House of Representatives for GroenLinks; some days earlier his predecessor Jolande Sap was forced to step down as leader in the House of Representatives for GroenLinks by the board of the GroenLinks party.