First elected in 1999, Tánczos briefly lost his seat in the 2005 General Election, but returned to Parliament following the sudden death of Rod Donald just prior to the first sitting of Parliament, as he was next ranked on the party list. In 2006, he contested the male co-leadership of the Green Party, but was beaten by non-MP Russel Norman in a STV vote by delegates from electorates around the country at the 2006 AGM. In 2008, he resigned from Parliament, though he intended to remain a political activist.