In a deliberative mini-public, a representative number of citizens receive information and discuss given policy topics in facilitated small groups. Typically, mini-publics are most effective politically and can have the most impact on policy-making when they are connected to democratic decision-making processes. Theorists have put forward possible mechanisms that may enhance this linkage, one of which is involving politicians within mini-publics with citizens. However, although much research to date has focussed on mini-publics with many citizen participants, there is little analysis of mini-publics with politicians as coparticipants. In this study, we ask how involving politicians in mini-publics influences both participating citizens' opinions and citizens' and politicians' perceptions of the quality of the mini-public deliberations. We organised an online mini-public, together with the City of Turku, Finland, on the topic of transport planning. The participants (n = 171) were recruited from a random sample and discussed the topic in facilitated small groups (n = 21). Pre- and postdeliberation surveys were collected. The effect of politicians on mini-publics was studied using an experimental intervention: in half of the groups, local politicians (two per group) participated, whereas in the other half, citizens deliberated among themselves. Although we found that the participating citizens' opinions changed, no trace of differences between the two treatment groups was reported. We conclude that politicians, at least when they are in a clear minority in the deliberating small groups, can deliberate with citizens without negatively affecting internal inclusion and the quality of deliberation within mini-publics.