Roman Catholic leaders in Iowa will call for candidates for president to follow the teachings of Pope Francis, and focus as much on the environment and income inequality in 2016 as they have in past elections on opposing gay marriage and abortion.

Bishop Richard Pates of Des Moines says the vocal pivot to be made Thursday will mark the first time a U.S. Catholic bishop has publicly asked those seeking the White House to heed the admonitions of Francis' first encyclical.

In it, the pope called for a "bold, sweeping revolution" to correct what he sees as a "structurally perverse" economic system that has turned the Earth into an "immense pile of filth."

Says Pates: "The goal of the pope is to raise the questions with all the candidates."