A top Vatican cardinal has expressed skepticism about ordaining married men to address the priest shortage in the Amazon, defending the value of priestly celibacy on the eve of a big Vatican meeting where the issue is officially on the agenda.

Cardinal Marc Ouellet on Wednesday launched his book "Friends of the Bridegroom: For a Renewed Vision of Priestly Celibacy." It addresses challenges facing priests amid a decline in vocations and reputational damage from sex abuse scandals.

Ouellet, a Canadian who heads the Vatican's bishops' office, said he wasn't opposed to a debate about ordaining married men at this month's synod on the Amazon.

Pope Francis poses with members of a Bavarian Orchestra from Augsburg, Germany, at the end of his weekly general audience in St. Peter's Square at the Vatican, Wednesday, Oct. 2, 2019. (AP PhotoAlessandra Tarantino)

Pope Francis poses with members of a Bavarian Orchestra from Augsburg, Germany, at the end of his weekly general audience in St. Peter's Square at the Vatican, Wednesday, Oct. 2, 2019. (AP PhotoAlessandra Tarantino)

But he said he was skeptical given the region doesn't even have enough catechists to teach lay people about their faith, much less train priests.

Pope Francis is hugged by Chinese faithful coming from the Tuscany city of Prato, at the end of his weekly general audience in St. Peter's Square at the Vatican, Wednesday, Oct. 2, 2019. (AP PhotoAlessandra Tarantino)

Pope Francis is hugged by Chinese faithful coming from the Tuscany city of Prato, at the end of his weekly general audience in St. Peter's Square at the Vatican, Wednesday, Oct. 2, 2019. (AP PhotoAlessandra Tarantino)