In 2013, he intervened in the political campaign to alter the Croatian referendum so that it more explicitly defined marriage only as a union between a man and a woman. He issued a pastoral letter to be read in all Catholic churches across the country reminding parishioners that "Marriage is the only union enabling procreation". The referendum was subsequently approved by a vote of 66% to 34%; and was thus regarded as a major victory for the Roman Catholic Church, and a blow to gay rights advocates.