Pittsburgh Steelers chairman emeritus Dan Rooney is resigning as U.S. ambassador to Ireland after serving in that role since 2009. Rooney, 80, will return to Pittsburgh and could be in Dallas on Sunday when the Steelers play the Cowboys. "I have had a lifelong commitment to advancing the relationship between the American and Irish people and building peace on this beautiful island, but came unexpectedly into politics and diplomacy," Rooney said in a op-ed piece for the Pittsburgh Post-Gazette. Rooney traveled often to the United States to attend Steelers games while serving in Ireland. Rooney and son Art II, the team's president, hold a 30 percent stake in the team.