From the church’s website:
The First Presidency of The Church of Jesus Christ of Latter-day Saints issued the following statement today. This is a statement of principle in anticipation of the expected debate over same-gender marriage. It is not an endorsement of any specific amendment.
“The Church of Jesus Christ of Latter-day Saints favors a constitutional amendment preserving marriage as the lawful union of a man and a woman.”
Thanks to Lyle Stamps for the tip.