President Barack Obama with Steelers boss Dan Rooney

Dan Rooney was sworn in as U.S. Ambassador to Ireland by Senator Hillary Clinton in a ceremony that took place in the Treaty Room at the State Department today.

"I could not be more delighted than to make official what is going to be so well received in Ireland and means so much to Americans, not only Irish Americans but all Americans, and that is the swearing-in of our new ambassador to Ireland,” said Clinton of Rooney’s appointment.

The former first lady paid compliment to Pittsburgh and to the “man behind the Steelers,” and complimented Rooney for co-founding the American Ireland Fund in the mid-1970s.

She also thanked Irish Ambassador to the U.S. Michael Collins and the Irish charge d'affaires McDaid for being present, and told them what to expect from Rooney's appointment.

“Today, chargé McDaid, we are sending you one of our very best. There is no greater champion of Irish-American relations than Dan Rooney”, said Clinton.

"The friendship between Ireland and the United States is vital to both of our nations, and President Obama and I are confident that that it will deepen with Dan and Patricia Rooney in Dublin.”

Clinton then administered the oath to Rooney, who solemnly repeated the words of the Secretary of State, thus becoming the 27th U.S. ambassador to Ireland.

Rooney, who traces his Irish roots to Newry in County Down, will take up residence in Phoenix Park. He is expected to arrive in Dublin tomorrow and will present his credentials to President McAleese on July 3 before officially assuming his duties. One of his first tasks will be to host the official reception for Independence Day on Friday evening.