The first real breakthrough for the party in Norwegian politics came in the 1987 local elections, when the party nearly doubled its support from 6.3% to 12.3% (county results). This was largely as immigration was for the first time seriously taken up as an issue by the party (although Hagen had already in the late 1970s called for a strongly restrictive immigration policy),[44] successfully putting the issue on the national agenda.[49] Its campaign had mainly been focused on the issue of asylum seekers,[50] but was additionally helped by the infamous "Mustafa-letter", a letter read out by Hagen during the electoral campaign that portrayed the future Islamisation of Norway.[40][51] In April 1988 the party was for the first time the second largest party in Norway in an opinion poll with 23.5%.[43] In September 1988, the party further proposed in parliament for a referendum on the immigration policy, which was regarded by political scientists as the start of the party's 1989 election campaign.[52] In 1989, the party made its breakthrough in national politics. In the 1989 parliamentary election, the party obtained 13%, up from 3.7% in 1985, and became the third largest party in Norway.