Turkey's president is on his way to Italy to meet Pope Francis at the Vatican, where the status of Jerusalem is expected to top their agenda Monday.

President Recep Tayyip Erdogan said before leaving Turkey on Sunday that the United States is "alone" in the Trump administration's decision to recognize Jerusalem as Israel's capital.

Erdogan said Turkey leads 1.7 billion Muslims worldwide since the country currently holds the term presidency of the Organization of Islamic Cooperation and the pope is "number one" among Catholics.

He noted: "These two important blocks are in fact decisive elements in this region," emphasizing Jerusalem's importance to several world religions.

Syria, the migrant crisis, Islamophobia and racism also are on Francis and Erdogan's discussion list.

Erdogan is scheduled to meet Italy's president and prime minister.