This paper examines key marginal seats during the 2013 federal election using content analysis and Vote Compass’ ‘big data’ to map Australian voters’ responses to asylum seeker boat arrivals. Vote Compass electoral tool was used for the first time in Australia during the 2013 election campaign hosted online by the national broadcaster, the Australian Broadcasting Corporation. Vote Compass was filled in more than 1.4 million times, enabling users to identify political parties’ policy positions, and their own, during that campaign. This article finds that the Australian Labor Party was effectively wedged during the 2013 campaign on the issue of asylum seeker policy with many party supporters politically divided on the party’s policy position. It also finds voters’ negative attitudes toward asylum seekers in marginal electorates had an effect on vote intention in the 2013 election campaign when other demographic factors are taken into consideration.