Politicians and other political speakers must engage in discursive work to construct themselves and the claims they offer as ‘reasons for action’ as credible. This is particularly the case when the action being proposed is high-stakes and/or when audiences are generally sceptical. The discursive means available to political speakers in this regard have been investigated in pragmatics, social psychology and critical discourse analysis. Broadly, two competing strategies can be identified: subjectification versus objectification. Both strategies function to elevate the epistemic status of the proposition advanced, thereby strengthening the justificatory case for action that it seeks to build. Subjectification strategies appeal to the personal authority of the speaker as a reason to believe the claim while objectification strategies appeal to third-party sources or other external evidentiary bases in support of the claim. In this study, we use experimental methods to compare empirically the effectiveness of these two alternative strategies. We do so in the context of political discourse seeking sanction for military action. Results show that, regardless of the credibility of the speaker, objectification strategies are more effective than subjectification strategies.