Joint gatherings of Congress for dignitaries' speeches are usually a recipe for competing partisan ovations and chummy backslaps and handshakes.
This time, House and Senate leaders have asked lawmakers: Please, not when the pope is here.
The leaders sent an appeal to lawmakers in advance of Pope Francis' speech Thursday morning, asking them to act with decorum in his presence. Among the no-no's — reaching out for handshakes or conversation with the pope and those accompanying him as they walk down the center aisle of the grand House chamber.
To drum the lesson in, the leaders' letter reminded legislators that the historic event will be seen on television "around the whole world and by many of our constituents."
Leaders have made similar appeals for State of the Union addresses, with little luck.
Francis' speech to Congress is a personal and political coup for House Speaker John Boehner, an Ohio Republican and Catholic.
Boehner unsuccessfully invited the two previous popes, John Paul II and Benedict XVI, to speak. He began trying in 1994 during his second House term, organizing a petition by lawmakers saying John Paul II was a "world leader, ambassador of peace and an important catalyst in the fall of the Iron Curtain."
Francis is the fourth pope to meet with a president in the U.S., including presidential visits on six separate trips by John Paul II.
The first was Paul VI's 1965 New York meeting with President Lyndon Johnson. Benedict XVI met President George W. Bush in 2008. Francis' coming speech at the United Nations will be the fifth by a pope.
Meanwhile, Senate Majority Leader Mitch McConnell marked Francis' visit to the Capitol in the modern way Thursday morning: on YouTube.
The Kentucky Republican said in a video that Francis' elevation to pope "heralded a new beginning for Catholics in Kentucky, across America and from every corner of the world."
McConnell praises the pope's "unique and engaging style" and says Americans have watched the pope reach new and different audiences, "both from within his flock and far beyond it."
A Baptist, McConnell says Americans from every faith and ?nearly every walk of life will gather at the Capitol as Francis becomes the first pope to address Congress.