Obama has cancelled his participation at the planned European Union - United States summit in Madrid. The president's appointment calender is "full." With his popularity shrinking in US public opinion polls, the last thing Obama needs is a photo op in Europe without prospects for any concrete results. One problem is that the Europeans are often more concerned with petty disputes over protocol and formalities than the actual substance of talks. This time around, EU leaders bickered over the question of who would get to shake the American president's hand first and who would get to say "Hello" and "Welcome".