This study explores agenda-setting dynamics between mainstream and niche parties on two issues owned by niche parties: immigration and European integration. It proposes an analytical distinction between opposition and government parties to understand which mainstream parties will engage in dialogue on these issues. Building on prospect theory, mainstream opposition parties (MOPs) are expected to be risk-acceptant and inclined to follow the agenda of niche competitors. Conversely, mainstream government parties (MGPs) are risk-averse, will systematically ignore shifts in the agenda of niche parties and only increase their attention in response to MOPs. Time-series analyses between 1974 and 2003 on the case of Denmark confirm the hypotheses.