Social media is increasingly being used by science communicators, journalists and government agencies to engage in discourse with a range of publics. Despite a growing body of literature on Twitter use, the communication of science via Twitter is comparatively under explored. This paper examines the prominence of scientific issues in political debate occurring on Twitter during the 2013 and 2016 Australian federal election campaigns. Hashtracking of the umbrella political hashtag auspol was used to capture tweets during the two campaign periods. The 2013 campaign was particularly relevant as a major issue for both parties was climate change mitigation, a controversial and partisan issue. Therefore, climate change discussion on Twitter during the 2013 election was used as a focal case study in this research. Subsamples of the 2013 data were used to identify public sentiment and major contributors to the online conversation, specifically seeking to see if scientific, governmental, media or ‘public' sources were the more dominant instigators. We compare the prominence of issues on Twitter to mainstream media polls over the two campaign periods and argue that the potential of Twitter as an effective public engagement tool for science, and for politicised scientific issues in particular, is not being realised.