The state House on Wednesday approved an amendment to the Kansas Constitution banning gay marriage and civil unions, placing the measure on the April 5 ballot.
The vote was 86-37, three more than the two-thirds majority necessary.
The proposed amendment declares that only couples in a traditional marriage of one man and one woman are entitled to the benefits associated with marriage. The Senate approved the measure last month.
Thirteen states adopted such amendments last year.
Since 1867, Kansas law has recognized only marriages between one man and one woman. Supporters of the amendment argued that the additional language would protect the state’s traditional definition of marriage from legal challenges.
Also Wednesday, a similar constitutional change failed in the Idaho Senate, which could not muster the two-thirds majority to send a same-sex marriage ban to a public vote.