Obama greets the locals after speaking at an Irish celebration at College Green in Dublin, May 23, 2011. Obama sipped a pint of stout and cuddled babies as a tiny Irish village welcomed home "a long lost cousin" with an outpouring of affection. Obama began his four-nation tour of Europe with a celebration of his ancestral roots. (Larry Downing/Reuters)
A newspaper vendor holds up a stack of papers with the front page headline "Welcome Home" in reference to US President Barack Obama's visit to the Republic of Ireland. Obama paid a joyful visit to a small Irish village where his great-great-great grandfather once lived and worked as a shoemaker.(Matt Dunham/Associated Press)
Obama high-fives a crowd after speaking during an Irish celebration at Green College, May 23, 2011. The visit to Ireland is the first stop on Obama's week-long European tour. (Jewel Samad/AFP/Getty Images)
Youths wear the Stars and Stripes as they wait for US President Obama in Dublin, May 23, 2011. (Peter Macdiarmid/Getty Images)
An Irish youngster poses for a photograph amongst people queuing up to join the crowd to listen to US President Barack Obama make an address at College Green in Dublin, May 23, 2011. (Matt Dunham/Associated Press)
A man hangs the Stars and Stripes bunting, May 23, 2011. (Peter Macdiarmid/Getty Images)
Children wave flags as they queue to see US President Obama address a rally at College Green, May 23, 2011. (Carl de Souza/AFP/Getty Images)
Irish President Mary McAleese and US President Barack Obama return to the Presidential Residence after a tree planting ceremony, May 23, 2011. (Peter Muhly/AFP/Getty Images)
A Secret Service agent holds the door of the US President as he leaves Winfield House, the official residence of the US Ambassador, in Regent's Park, May 24, 2011 in London, England. The 44th President of the United States, Barack Obama, and his wife Michelle are in the UK for a two day State Visit at the invitation of HM Queen Elizabeth II. During the trip they will attend a state banquet at Buckingham Palace and the President will address both houses of parliament at Westminster Hall. (Dominic Lipinski/WPA Pool/Getty Images)
Obama reviews an honor guard with Prince Phillip, Duke of Edinburgh, during an official arrival ceremony at Buckingham Palace, May 24, 2011. (Larry Downing/Reuters)
An honor guard passes before Britain's Queen Elizabeth II and US President Barack Obama at Buckingham Palace, May 24, 2011. Obama is on a four-nation European visit to Ireland, England, France and Poland. (Kevin Lamarque/Reuters)
A muslim protestor is removed by police from outside Downing Street prior to the arrival of President Obama, May 24, 2011 in London, England. (Jeff J Mitchell/Getty Images)
First Lady Michelle Obama, Prime Minister David Cameron, President Obama and Samantha Cameron pose outside number 10 Downing Street, May 24, 2011. (Dan Kitwood/Getty Images)
Obama stands at the altar as he walks with the Dean of Westminster, Dr. John Hall as he visits Westminster Abbey, May 24, 2011. (Charles Dharapak/Associated Press)
Obama shakes hands with the choristers in Westminster Abbey, May 24, 2011 in London, England. (Oli Scarff/Getty Images)
President Obama is shown around Westminster Abbey by the Dean of Westminster, Dr John Hall (with his wife Michelle), May 24, 2011 in London, England. (Matthew Lloyd/Getty Images)
Obama, watched by his wife, First Lady Michelle Obama, signs the Distinguished Visitors Book during a tour of Westminster Abbey, May 24, 2011. Obama mistakenly dated the visit 24 May 2008. (John Stillwell/Pool/Associated Press)
A detailed view of the page written by US President Barack Obama, in Westminster Abbey's Distinguished Visitor's Book shows the incorrect date 24 May 2008. (Oli Scarff/Getty Images)
US Secretary of State Hillary Clinton looks at paintings inside Buckingham Palace after lunch in London May 24, 2011. (Larry Downing/Reuters)
US President Barack Obama and First Lady Michelle Obama tour the Queen's Gallery with Queen Elizabeth II and Prince Phillip, Duke of Edinburgh, at Buckingham Palace, May 24, 2011. (Larry Downing/Reuters)
The US President and First Lady Michelle Obama meet Britain's Prince William, the Duke of Cambridge and his wife Catherine, Duchess of Cambridge at Buckingham Palace, in central London, May 24, 2011. Obama took time out to say he was "heartbroken" at the toll of vicious tornados which ripped across the US midwest, killing 116 people. (Charles Dharapak/AFP/Getty Images)
A police officer pushes back demonstrators after clashes between the English Defence League and muslim groups, in London, May 24, 2011. (Darren Staples/Reuters)
A Secret Service agent polishes the Presidential limousine outside Westminster Abbey, May 24, 2011. (Peter Macdiarmid/Getty Images)