Political parties and voters have to deal with exogenous shocks during electoral campaigns. In addition, electoral campaigns are increasing in terms of time and issues. Decentralization and nationalism in multilevel countries is still outstanding issue. Dealing with ethno-regionalist parties claims and the voters’ sense of belonging from the state-wide parties builds interest and differences across countries and parties. Party and voters positions over nationalism have been changing over time. Have the voters more radicalized positions over nationalism feeling to differentiate from their opponents? Or are they trying to maintain the “median” position? The primary assumption is that voters change their position over nationalism due to referendums. To predict voters’ positions over nationalism, I use data from public opinion surveys from the United Kingdom and Spain. I analyze voters and parties positions over nationalism, and the ideological (traditional left-right) scales to find differences in the voters’ self-location and parties’ position before and after referendums. I expect that voters have a radicalized –understood as more extreme- position over nationalism and ideology during the period after the referendums. These results hold relevant implications for studying voters and political parties’ placement over different scales in multilevel countries. Also, the analysis of referendums as a critical shock appears to contribute to the political behaviour field.