The rapid adoption of marriage equality legislation for non-heterosexual individuals in Europe is attributed to many factors, including dramatic shifts in public opinion, the work of transnational activists and changing international norms. Usually, these factors must be filtered through the halls of parliaments where most policy change happens. Given the importance of parliamentarians’ attitudes, it is surprising that we know so little about how attitudes towards same-sex marriage are distributed across political candidates in Europe and what factors shape them. This article fills that gap by using an underutilised dataset on the political preferences of candidates for parliamentary office. We find that beyond attachment to party families, a candidate’s religiosity and practice has a greater effect on a would-be Member of Parliament’s attitudes towards same-sex marriage. The findings suggest that the success of parliamentary action on lesbian, gay, bisexual and transgender rights depends not on the partisan composition of the legislature, but rather on the representation of secular candidates.<br /><br />Key messages<br /><ul><li>Support among parliamentary candidates aspiring to become legislators is an important prerequisite for the advancement of lesbian, gay, bisexual and transgender rights in polities where institutional equality is brought about via legislative reforms.</li><br /><li>Over and above partisanship attachment and ideological positions, the religiosity of would-be Members of Parliament is important in establishing support for same-sex marriage.</li><br /><li>The secular composition of legislative chambers, rather than its partisan composition, is more likely to predict the success of the advancement of lesbian, gay, bisexual and transgender rights.</li></ul>

An extensive literature has formed that shows and explains why public opinion about LGBTQ rights has changed to dramatically and quickly. One of the effects has been the passage of numerous pieces of legislation that grant sexual minorities equal treatment. To advance the legal protection and egalitarian treatment afforded to LGBTQ citizens, activists need allies in parliament. This paper investigates what affects the views of parliamentary candidates on gay rights, independent of public opinion. Because in most parliamentary systems parties select their candidates, we would expect political ideology to play a strong role in shaping their views. However, drawing on rarely used data on the views and background of thousands of individual parliamentary candidates from countries across Europe and their policy preferences on the issue of same-sex marriage, our results show that political ideology and partisanship do not tell the whole story. Empirically, we demonstrate that parliamentary candidates' positions on same-sex marriage are determined more by their religious beliefs and other socio-demographic characteristics than by political ideology, even within parties traditional supportive of progressive social values. This study contributes to better understanding how LGBTQ policy change happens in Europe by examining the preferences of the people mainly responsible for it.