His pilgrimage this week is also a chance to reassure Jews and Muslims about Vatican views.
For a friendly foreign leader, a visit to the White House can be a visit to the woodshed.
Older leaders among the minority aim to peacefully address discrimination but warn that younger Shiites are pushing for militancy.
The president will meet with three leaders from the region in coming weeks. Meanwhile, special envoy George Mitchell finds it tough going.
After meeting with Jordan's King Abdullah II, he emphasized his commitment to Palestinian statehood – a top concern among Arabs.
It's about Iran, Iraq, and Israel. The two foes planned to meet in Riyadh Wednesday to solidify Arab unity amid regional volatility.
The incident highlights a shift from unquestioned deference toward the royal family.