Vice President Joseph Biden places his hand on his heart as the casket of his son is carried into the church before a funeral mass for former Delaware Attorney General Beau Biden at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Bryan Woolston TPX IMAGES OF THE DAY

U.S. President Barack Obama (R) hugs Vice President Joe Biden during the funeral of his son former Delaware Attorney General Beau Biden as Biden's widow Hallie (L) passes her husband's casket at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY 

U.S. President Barack Obama kisses Vice President Joe Biden on the cheek as he hugs him after delivering the eulogy during the funeral of Biden's son, former Delaware Attorney General Beau Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY 

U.S. President Barack Obama pauses as he delivers the eulogy during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY 

Vice President Joe Biden (R), puts his hand on his heart as he and granddaughter Natalie and stepmother Jill Biden look on before a funeral mass for former Delaware Attorney General Beau Biden, son of Vice President Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Bryan Woolston

Former U.S. President Bill Clinton (L) and Democratic presidential candidate Hillary Clinton (R) watch as the casket of former Delaware Attorney General Beau Biden, son of Vice President Biden, is taken from his funeral at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

Chris Martin of the band Coldplay sings the song "Til' Kingdom Come" during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

A procession carrying the casket leaves the church after the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Doug Mills/Pool 

A member of a U.S. military color guard holds the flag from the casket during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

U.S. President Barack Obama hugs his daughter Sasha as they and first lady Michelle Obama (R) watch as the casket of former Delaware Attorney General Beau Biden, son of Vice President Biden, leaves his funeral at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

Vice President Joe Biden attends the funeral of his son, former Delaware Attorney General Beau Biden at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Doug Mills/Pool 

U.S. Vice President Joe Biden (R) stands with his son's brother Hunter (C) and widow Hallie (2nd R) as his son's casket is taken from a hearse before a funeral mass for former Delaware Attorney General Beau Biden, son of Vice President Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Bryan Woolston

U.S. Army Chief of Staff General Raymond Odierno delivers a eulogy during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

U.S. President Barack Obama hugs Vice President Joe Biden after delivering the eulogy during the funeral of Biden's son, former Delaware Attorney General Beau Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

Vice President Joe Biden and his wife Jill Biden leave following the funeral for former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Pablo Martinez Monsivais/Pool 

Singer Chris Martin of the band Coldplay hugs Vice President Joe Biden after performing the song "Til' Kingdom Come" during the funeral of Biden's son, former Delaware Attorney General Beau Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

U.S. President Barack Obama a eulogy during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

U.S. Vice President Joe Biden (R) waves next to President Barack Obama (L) during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Yuri Gripas/Pool 

U.S. President Barack Obama hugs Jill Biden during the funeral of Biden's stepson, former Delaware Attorney General Beau Biden, as his brother Hunter Biden (L) reaches out to the president at St. Anthony of Padua church in Wilimington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

A procession carrying a casket enters the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Yuri Gripas/Pool 

Vice President Joseph Biden (R) greets clergyman after a funeral mass for former Delaware Attorney General Beau Biden, son of Vice President Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Bryan Woolston

Vice President Joe Biden's grandaughters Naomi, Maisy and Finnegan Biden participate in a reading during their uncle Beau Biden's funeral in Wilmington, Delaware in St. Anthony of Padua church in Wilmington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

President Barack Obama arrives at the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 5, 2015. REUTERS/Doug Mills/Pool 

U.S. President Barack Obama, along with first lady Michelle Obama (2nd R) and their daughter Sasha (R) attends the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 5, 2015. REUTERS/Yuri Gripas/Pool 

The casket of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, arrives at his funeral in St. Anthony of Padua church in Wilmington, Delaware June 6, 2015. REUTERS/Kevin Lamarque 

President Barack Obama watches the casket arrive during funeral services for former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 5, 2015. REUTERS/Pablo Martinez Monsivais/Pool 

U.S. President Barack Obama (R) hugs Vice President Joe Biden during the funeral of former Delaware Attorney General Beau Biden, son of Vice President Joe Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Yuri Gripas/Pool 

(L-R) Beau Biden's brother Hunter (top L), son Hunter (bottom L), widow Hallie, Vice President Joe Biden and daughter Natalie look on before a funeral mass for former Delaware Attorney General Beau Biden, son of Vice President Biden, at St. Anthony of Padua Church in Wilmington, Delaware June 6, 2015. REUTERS/Bryan Woolston