President Obama holds out his hand to shake Russian President Vladimir Putin's during a bilateral meeting at the G-20 summit on Monday, June 18, 2012, in Los Cabos, Mexico. (Associated Press)
Treasury Secretary Timothy F. Geithner confers frequently with European leaders, but the U.S. has limited leverage in the upcoming G-20 summit. (Associated Press)
Riot police seize a protester at the G-8 and G-20 summits in Toronto in 2010. Protests at this month's NATO Summit in Chicago will miss an opportunity to double up on the G-8 because President Obama moved it to Camp David. (Associated Press)
U.S. Treasury Secretary Timothy F. Geithner speaks at a meeting of the G-20 in Mexico City. He wants the EU to provide more debt-crisis stabilizing funds. (Associated Press)
President Obama and French President Nicolas Sarkozy hug as they attend a French-U.S. alliance ceremony at the Cannes City Hall on Friday, Nov. 4, 2011, after the end of the second day of the G-20 summit. (AP Photo/Philippe Wojazer, Pool)
South Korean President Lee Myung-bak (left) speaks with Chinese President Hu Jintao during a roundtable meeting at a G-20 summit in Cannes, France on Nov. 4, 2011. (Associated Press)
Greek Prime Minister George Papandreou speaks with the media as he leaves a G-20 summit in Cannes, France, on Wednesday, Nov. 2, 2011. (AP Photo/Markus Schreiber)
President Obama (left) and French President Nicolas Sarkozy make statements to reporters at the G-20 summit in Cannes, France, on Thursday, Nov. 3, 2011. (AP Photo/Charles Dharapak)
French President Nicolas Sarkozy (center) speaks with German Chancellor Angela Merkel during arrivals for the G-20 economic summit in Cannes, France, on Wednesday. (Associated Press)
French President Nicolas Sarkozy speaks with German Chancellor Angela Merkel during arrivals for the G-20 economic summit in Cannes, France, on Wednesday. (Associated Press)
** FILE ** In this Sept. 24, 2009, file photo, President Barack Obama welcomes China's President Hu Jintao as he arrives for the G-20 summit dinner in Pittsburgh. (AP Photo/Charles Dharapak, File)
** FILE ** Indian Prime Minister Manmohan Singh arrives for the opening plenary session of the G-20 summit at in Seoul on Friday, Nov. 12, 2010. (AP Photo)