This thesis was undertaken to examine the role of the social media forum, Twitter, in the 2015 UK general election. The research, conducted during the campaign, focused on the official party pages of the Conservatives, Labour, Liberal Democrats, and United Kingdom Independence Party (UKIP) and their candidates standing in target seats. The thesis contributes to an ongoing academic debate concerning the potential for the internet and social media to transform political communication. The theoretical framework draws on the work of the philosopher Jürgen Habermas and his concepts of ‘rational-critical debate’ and the ‘public sphere’. Although Habermas’ theory pre-dates the internet, his insights provide invaluable criteria by which the practical impact of social media, as opposed to its undeniable promise as a 'transformative' promoter of political debate in a liberal democracy, can be judged.

I examine Twitter’s design architecture, which has been heavily influenced by its users and, at least in theory, constitutes an open forum for the free exchange of ideas and opinions envisaged by Habermas. Chapter Five explores the use of these features by the main UK parties in 2015. An analysis the content of the tweets in Chapter Six explores how the parties engaged with different election issues on the site, considering the extent to which they reacted to public opinion and events, or tried to retain control of this aspect of their campaigns. Chapter Seven examines the use of Twitter by individual candidates, reviewing their engagement with the site’s design features and their coverage of election issues. This chapter focuses on the potential conflict between the candidates’ roles as local campaigners and their status as representatives of the national parties. Overall, the findings arising from the empirical research suggested that the major parties regarded Twitter as a means of promoting their own favoured agendas rather than a venue for 'rational-critical debate'. Nevertheless, the site offers considerable potential for future research into the use of social media in political campaigning in the UK, while an analytical framework based on Habermas' ideas could usefully be applied to other internet platforms.