WASHINGTON (Reuters) - House of Representatives Speaker John Boehner said on Thursday he has invited Pope Francis to address a joint session of Congress when he visits the United States.

The pontiff is widely expected to travel to the United States in September 2015 to attend the World Meeting of Families in Philadelphia, and mayors of several other U.S. cities have also invited him to visit.

Boehner, the highest-ranking Catholic currently elected to U.S. public office, moved to secure a spot on the Pope's itinerary in a letter to Francis released on Thursday.

"It is with reverence and admiration that I have invited Pope Francis, as head of state of the Holy See and the first Pope to hail from the Americas, to address a joint meeting of the United States Congress," Boehner said in a statement.

"Pope Francis has inspired millions of Americans with his pastoral manner and servant leadership, challenging all people to lead lives of mercy, forgiveness, solidarity, and humble service," Boehner added.

But the Ohio Republican also used the occasion to reiterate Republicans' views that increasing government programs and welfare is not the way to meet Americans' responsibility to care for the poor and the most vulnerable.

He said Americans "have embraced Pope Francis' reminder that we cannot meet our responsibility to the poor with a welfare mentality based on business calculations. We can meet it only with personal charity on the one hand and sound, inclusive policies on the other."

President Barack Obama is scheduled to meet with the Pope on March 27 at the Vatican while he is on a trip to Europe.

(Reporting By David Lawder; Editing by Sandra Maler and David Storey)