Kateřina Jacques joined the Green Party in spring 2005 and was elected to the central revision committee at their congress in August 2005. In the primary election in January 2006 she received the second eligible place on the Green ticket, just after chairman Martin Bursík. The Green Party places emphasis on representation of women, and the young and photogenic Jacques was featured in Prague election campaign posters and was accompanied by Bursík on billboards of the Green Party. She received 6,926 preferential votes (11.46% of the total for the Green Party), 185 more than Bursík, so she overtook him in the order for assigning mandates.