Barack Obama appeals for a free kick after a Belgian foul as he joins staff for a few minutes at a viewing party, July 1, 2014. [Photo/Agencies]

US President Barack Obama took a break from affairs of state to pop into a White House staff party to watch part of the World Cup soccer match between the US and Belgium. He arrived shortly after the second half began, having wrapped up a meeting with national security aides.

Obama began chanting: "I believe that we can win!" joining some 200 members of staff packed into the auditorium of the Eisenhower Executive Office Building. Earlier in the day the president had told reporters he had scheduled a cabinet meeting in the morning as "America will be busy this afternoon".

Despite having the support of the commander-in-chief, the US was eventually eliminated by Belgium, 2-1 after extra time. The president had watched some of the team's previous match, against Germany, on his way to Minnesota in the presidential aircraft, Air Force One.

After the first 32 matches, the World Cup averaged 4.3 million viewers on ESPN, up 50 percent from the nearly 2.9 million for matches in the 2010 edition.

FIFA secretary-general Jerome Valcke expressed surprise at American people's World Cup enthusiasm this year, with US TV ratings for soccer matches higher than the NBA finals and attracting more viewers than baseball games.