By Paul Kane May 30 at 11:15 PM

Joseph Robinette “Beau” Biden III, the son of Vice President Biden and former state attorney general of Delaware, died Saturday after battling brain cancer for several years.

Biden, 46, the oldest son of the vice president and the rising star of a family dynasty, had been admitted recently to Walter Reed National Military Medical Center in Bethesda as he fought the cancer, a battle that his father largely kept private in the last weeks as his son clung to 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, Natalie and Hunter,” Vice President Biden said in a statement that was released Saturday night.

Beau Biden, a major in the Delaware Army National Guard’s Judge Advocate General Corps, became one of his state’s most popular public figures and had been considered the front-runner for the 2016 race to become the state’s next governor, but in August 2013 he was admitted to one of the world’s most renowned cancer treatment centers, MD Anderson Cancer Center in Houston, to begin his fight with the disease.

According to the vice president’s office, Beau Biden underwent surgery in Houston in 2013 and then followed a normal course of radiation and chemotherapy. By November 2013, he had been given a clean bill of health, but after a recurrence this spring, Biden began an aggressive treatment and was admitted to Walter Reed this month.

Biden is survived by his wife, Hallie, and two children.

President Obama released a statement late Saturday saying that he and first lady Michelle Obama were grieving and calling him “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.”

“But for all that Beau Biden achieved in his life, nothing made him prouder; nothing made him happier; nothing claimed a fuller focus of his love and devotion than his family,” Obama’s statement said.

Beau Biden became a national political star in 2008 after delivering a stirring introduction of his father at the Democratic National Convention in Denver the night Joe Biden accepted the nomination for vice president. A little more than a month later, Beau Biden deployed to Iraq and served there for one year — except for a trip home in January 2009 to see his father take the oath of office as vice president.

Beau Biden was awarded the Bronze Star.

In Denver seven years ago, Beau Biden told the tragic family story that became the emotional foundation for his father’s 36 years of service in the Senate and the past 6 1/2 years as vice president. Shortly after winning his Senate race, in December 1972, Joe Biden received a phone call while in Washington interviewing staff.

His wife, Neilia, and three children had been in a horrible car crash on the way home from purchasing the family Christmas tree. His wife and daughter had died, and his two sons, Beau and Hunter, were clinging to life. Having just turned 30, Joe Biden raced home to Wilmington and considered never taking the oath of office.

Through the support of other senators, Biden agreed to be sworn in the next month at the hospital bedside of Beau and Hunter. Eventually venturing to Washington, Biden decided that he would take the train every morning from Wilmington and return every night.

“As a single parent, he decided to be there to put us to bed, to be there when we woke from a bad dream, to make us breakfast, so he’d travel to and from Washington, four hours a day,” Beau Biden told the Denver crowd on Aug. 27, 2008, in the speech that introduced the world to a story that his father had told many times.

In recent weeks, the vice president’s public schedule had declined as he regularly visited his son. Two weeks ago, during Yale University’s graduation ceremonies, he delivered a deeply personal speech to thousands of students and parents who had no idea what the vice president was personally enduring.

Close advisers viewed it as the closest Joe Biden ever came to fully explaining how much his personal life and tragedy informed his own career. Of his Amtrak ride home every night to see his two sons, he said that it wasn’t for them.

“The real reason I went home every night was that I needed my children more than they needed me,” he told the Yale crowd.

Beau Biden attended his father’s high school, Archmere Academy, was class president and graduated from the University of Pennsylvania. He then got his law degree from Syracuse University, out of devotion to his deceased mother, who graduated from that college. Joe Biden, originally considering other law schools, decided to attend Syracuse Law after falling in love with Neilia Hunter.

Beau Biden was elected Delaware’s attorney general in 2006 and was considered the likely candidate to take his father’s Senate seat after he left to become vice president. Ted Kaufman — the vice president’s closest confidant and former chief of staff — was appointed as an interim senator, but eventually Beau Biden decided to run for reelection as attorney general in 2010 rather than try to claim his father’s Senate seat, charting his own political path toward one day becoming governor.

In recent weeks Kaufman has returned to Vice President Biden’s side, working with him again as he dealt with the looming tragedy of his son’s death.

“More than his professional accomplishments, Beau measured himself as a husband, father, son and brother. His absolute honor made him a role model for our family. Beau embodied my father’s saying that a parent knows success when his child turns out better than he did,” the vice president said Saturday in his statement.

Paul Kane covers Congress and politics for the Washington Post.