PARTY (UKIP) AND THE EU ISSUEThe 2010 general election provided further evidence of the development of multi-party politics in the United Kingdom. The Conservatives and Labour polled a combined post-war low of 65 per cent of the vote while small parties together scored 12 per cent but remained significantly underrepresented in the House of Commons. Having fallen short of a parliamentary majority, the Conservatives entered coalition with the Liberal Democrats. Beyond Westminster, multi-party politics is the norm in elections to the devolved assemblies, the European Parliament and many local authorities.The presence of niche parties changes the parameters of party competition. Meguid (2005) identifies green, ethno-regionalist and radical right parties as niche parties -that is, parties with a distinctive focus on a limited set of non-economic issues which lie beyond the traditional class cleavage and are largely ignored by mainstream parties. Adams et al (2006, 513) use a broader definition of niche parties as non-centrist or ideologically extreme parties, as does Wagner (2011, 3) who highlights their focus on non-economic issues. Hard Eurosceptic parties oppose European integration as embodied in the European Union (EU) or adopt policies tantamount to the current EU project (Taggart and Szczerbiak's 2008, 247-8). These parties do not feature prominently in this literature but, given their location on an anti-European integration versus pro-European integration cleavage and focus on an issue often ignored by mainstream parties, they fit the niche party criteria. However, hard Eurosceptic parties are not part of a coherent or extensive party family: hard Euroscepticism is found across the ideological spectrum and may be one of a set of positions rather than a party's guiding ethos. Although the EU issue remains their primary concern, the extension of EU competences has seen some hard Eurosceptic parties broaden their 2 focus. Hard Eurosceptic parties might thus be treated as a distinctive sub-set of niche parties .This article adds to the literature on party competition by examining the different strategies employed by mainstream and niche parties, using the Conservatives and UK Independence Party (UKIP) as a case study. European integration is the key issue in competition between the two, with UKIP supporting withdrawal from the EU. A number of caveats are required. The focus on the Conservatives and UKIP does not imply that David Cameron's modernisation project was flawed because it moved the Conservatives to the centre to compete with Labour. This was necessary, but not sufficient, for the Conservatives to regain power. However, the Conservatives' move to the centre and downplaying of the EU issue created space that UKIP has exploited. Nor do we suggest that the UKIP challenge is the main driver of Conservative strategy on the EU issue. Intra-party divisions and competition with Labour have been more significant, but Conservative responses to these also shaped its strategy towards UKIP. Finally we are not sugg...