In a quantitative study using unique quarterly data across two decades, this article addresses the opposition's opportunities to influence policy; a topic that has been neglected in existing party-policy research. The idea that is developed is applied to a remarkable policy development on crime during the Danish leftwing government in the 1990s. Contrary to its policy position when it took office in 1993, the leftwing government repeatedly adopted severe restrictions to penal policy. The policy position of the rightwing opposition and its vehement and persistent criticism of the government provide an explanation, the article argues. Taking media coverage, public opinion, violence statistics, and the government's performance into account, the analysis shows that opposition criticism spurred the penal policy restrictions. Hence, by incorporating a policy agenda perspective, this article encourages a broadening of the perspective on parties’ policy influence. In particularly the opposition's opportunities to politicise issues and hereby influence policy.