A lobby group established in 2013, "In the Name of the Family", led the call to change the Croatian national constitution so that marriage can only be defined as a union between a man and a woman. The Roman Catholic Church played a prominent role in this political campaign, and Cardinal Josip Bozanić of Zagreb issued a letter to be read in churches reminding people that "Marriage is the only union enabling procreation". Subsequently, a national referendum was held on 1 December 2013 where voters approved the change. Franko Dota, a gay rights activist, criticised the results, arguing that it was intended "to humiliate the gay population, and to strike against the progress of the past decades". Stephen Bartulica, a proponent of the referendum and a professor at the Catholic University of Croatia, countered that "the vote was an attempt to show that there is strong opposition" to "gay marriage and adoption by gays". The prime minister, Zoran Milanović, was unhappy that the referendum had taken place at all, saying, "I think it did not make us any better, smarter or prettier."