PITTSBURGH — Pittsburgh Steelers chairman and co-owner Dan Rooney has stepped down as the US ambassador to Ireland, a post he assumed after backing President Obama’s presidential campaign despite being a longtime Republican.

The embassy in Dublin said Rooney, 80, resigned Friday and returned to the United States. Press officer John Murphy said Rooney met with Ireland’s prime minister, Enda Kenny, and President Michael Higgins during a final round of engagements this week.