Attorney General Beau Biden (D-DE) (L) and Vice Presidential candidate Senator Joe Biden (D-DE) gesture on stage at the 2008 Democratic National Convention in Denver, Colorado in this August 27, 2008 file photo.  [Photo/Agencies]

President Barack Obama said he and his wife, first lady Michelle Obama, were grieving. He paid warm tribute to Beau Biden, saying he took after his father.

"He studied the law, like his dad, even choosing the same law school. He chased a life of public service, like his dad, serving in Iraq and as Delaware's Attorney General," Obama said in a statement.

"Like his dad, Beau was a good, big-hearted, devoutly Catholic and deeply faithful man, who made a difference in the lives of all he touched, and he lives on in their hearts."

The vice president has not publicly ruled out a run for president in 2016, but he would face tough odds to gain an advantage over his friend, former Secretary of State Hillary Clinton, who is far ahead in public opinion polls in the race for the Democratic presidential nomination.

Clinton expressed condolences over Twitter on Saturday.

"My heart is broken for the family of Beau Biden - a wonderful man who served his country with devotion and lived his life with courage," she wrote.

The vice president has faced family tragedy before.

Shortly after winning election to the U.S. Senate in 1972, his wife Neilia and three children were in a car crash. Neilia and their daughter were killed, while their two sons, Beau and Hunter, were injured.

Biden opted not to move to Washington, choosing instead to make the 2 1/2-hour daily round-trip train commute from Delaware to his Senate job so he could spend more time with his sons. He married Jill Jacobs some five years after his first wife died.

Biden took office as vice president when Obama entered the White House in January 2009. He has a deep knowledge of Washington politics after decades in Congress and a folksy, avuncular style that contrasts with what many consider Obama's more aloof manner.

Biden regularly mentions his family in speeches and sometimes has his grandchildren accompany him on diplomatic trips abroad.