Author and foreign-policy expert Samantha Power wasn't at Wednesday's screening of "Sergio," the documentary (competing the Sundance Film Festival) based on Power's biography of Sergio Vieira de Mello, the charismatic U.N. envoy who was killed in a 2003 car bombing in Baghdad.

Power was in Park City earlier in the festival, said director Greg Barker, when "she got a call from a guy in D.C., who said, 'Where are you?' " Power told the guy she was at Sundance, and the guy replied, "Don't you know there's a big party here?"

The guy making the call from D.C.? President Barack Obama.