Beau Biden, twice elected attorney general of Delaware and son of US vice president Joe Biden, has died aged 46 from brain cancer.
Mr Biden was diagnosed with brain cancer two years ago and was admitted to the Walter Reed National Military Medical Centre in Washington earlier this month.
He suffered a mild stroke in 2010 and underwent surgery three years later at a Texas cancer centre to remove what was described as a small lesion.
Mr Biden announced in 2014 that he would not seek a third term as attorney general and that he planned to run for governor in 2016.
Vice President Joe Biden said: "It is with broken hearts that Hallie, Hunter, Ashley, Jill and I announce the passing of our husband, brother and son, Beau, after he battled brain cancer with the same integrity, courage and strength he demonstrated every day of his life."
"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," he said.
Vice President Biden's loss of his son is his second as a father, as his infant daughter died in a car accident more than four decades ago.
President Barack Obama said: "Michelle and I humbly pray for the good Lord to watch over Beau Biden, and to protect and comfort his family here on Earth."
The Vice President said his son had dedicated his life to serving others during stints as a lawyer, a major in the Delaware National Guard and as state attorney general.
Beau Biden served a year-long deployment in Iraq and was awarded a Bronze Star.
He most recently was with the Wilmington, Delaware, law firm Grant & Eisenhofer, where he focused on securities litigation and whistle-blower cases.
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