The Presbyterian Church (U.S.A.)'s General Assembly on Friday rejected a proposal to change the denomination's definition of marriage to a "covenant between two people" from "a civil contract between a woman and a man" but decided to enter into a two year period of "study and discernment" over related issues.

The overture was rejected by the Assembly, gathering in Pittsburgh, by a vote of 338-308. Had the measure passed, a majority of the denomination's 173 presbyteries would have been required to approve the constitutional amendment.

Another measure, which also failed in the Assembly, would have issued an "authoritative interpretation" of scripture that would have allowed ministers residing in states where same-sex marriage is legal to preside at same-sex weddings.

On issues relating to sexuality within the church, the denomination voted two years ago to change ordination standards, removing a chastity requirement that allowed for the ordination of non-celibate gay clergy. The measure was adopted by a majority of presbyteries in 2011. The denomination currently allows ministers to bless same-sex unions.

The Rev. Neal Presa, moderator of the General Assembly and the Rev. Amee Moiso, moderator of the Committee on Civil Union and marriage issues, issued statements after the vote.

"Commissioners and advisory delegates wrestled and grappled very passionately and energetically around how the church can faithfully and fully respond around local realities around marriages and civil unions," said Rev. Presa, who is also a pastor for a congregation in New Jersey.

Rev. Moiso said the assembly is seeking a "third way forward" by entering into a period of "study and discernment" about the matter for the next two years.

"We brought several recommendations from the committee to the assembly but in the end, the assembly embraced a third way forward, a way that we might move together into study and discernment for two years by declining to re-affirm the traditional definition of marriage and by declining to embrace a new definition of marriage," said Rev. Moiso, a campus minister at Santa Clara University just South of San Francisco in Silicon Valley.

"It is clear that this assembly still seeks more discernment and clarity on the issue and thus we embrace this time of study and discernment together which will look at all the issues of marriage before us. From civil law to worship theology and sacraments, to how these issues get played out in our local congregations," she said.

Rev. Presa addressed the impact of the decision.

"We do realize that today's decision will cause grief and sadness among many in the church and for sessions, and for pastors and elders around the church who were hoping for some clear direction and guidance from this assembly. At the same time, we are united in seeking the unity of the spirit and the bond of peace and we hope and pray that the conversations that will be had across the church in the next two years, that we can find that unity with the Lord and the Holy Spirit leading us," he said.

The head of More Light Presbyterians, a group seeking "full participation" of lesbian, gay, bisexual and transgender persons in the church, expressed disappointment at the outcome, but said the group would keep working for change.

"While it is disappointing that the Church missed this historic opportunity to move toward full inclusion, the fact that so many Presbyterians from around the country called for the Church to recognize love between committed same-gender couples was awe-inspiring to see." said Michael J. Adee, Executive Director, More Light Presbyterians.

"We have more work to do to show those who oppose full inclusion how truly wonderful the gifts that committed, married same-sex couples bring to our church. We're inspired by the progress we've made together and are just as committed to continuing this work, together."