US President Barack Obama has visited Vice President Joe Biden and his family to offer condolences after the death of Mr Biden's son, Beau.
Beau Biden, 46, who served eight years as attorney general of Delaware, died on Saturday after a recurrence of brain cancer.
The vice president, in a statement on behalf of the Biden family, announced that: "The entire Biden family is saddened beyond words.
“We know that Beau's spirit will live on in all of us, especially through his brave wife, Hallie, and two remarkable children, Natalie and Hunter," the statement read.
It added that Beau "battled brain cancer with the same integrity, courage and strength he demonstrated every day of his life.”
Mr Obama and his wife, Michelle, went to the US Naval Observatory, the vice president's official residence, to offer their condolences to the Biden family.
The Obamas had been scheduled to host a reception at the White House today but it was canceled out of respect for the Bidens.
Other Washington officials and politicians took to social media to express their sympathies over the death of Beau, who was married and had two children.
Secretary of State John Kerry called him "a son any father might hope to raise" and recalled how Beau chose to continue serving in the military in Iraq rather than be appointed to the Senate seat his father was leaving to become vice president in 2009.
Senator Patrick Leahy, a long-time Senate colleague of JoeBiden, called Beau "an impressive, down-to-earth person and anatural leader."
Former President Bill Clinton and wife Hillary, who is running for the Democratic presidential nomination, offered condolences on Twitter, as did House Speaker John Boehner and potential Republican presidential nominees Jeb Bush, Scott Walker, Rick Santorum, and Mike Huckabee.
Beau Biden had a mild stroke in 2010 and was diagnosed with brain cancer in August 2013. After surgery, radiation and chemotherapy, he was given a clean bill of health but the cancer returned in spring of this year.
He served a year-long tour in Iraq as a member of the Delaware Army National Guard and had announced last year he planned to run for governor of Delaware in 2016.
As a boy, Beau and his brother survived a 1972 car accident that killed their mother and sister shortly after Joe Biden had been elected to the Senate.