Washington: Joe Biden, whose life has been marked by triumph and tragedy, is on the brink of winning a prize that has eluded his grasp on two previous occasions — the Democratic presidential nomination.
The 77-year-old moderate Democrat moved a step closer to heading the party ticket against Donald Trump in November with a series of primary wins on Tuesday over the leftist Bernie Sanders.
One of the youngest senators in US history, vice president for eight years to Barack Obama, America's first black president, Biden has had a storied political career.
His two previous White House runs — in 1988 and 2008 — ended in humiliation, however, as the then senator from Delaware failed to win a single state primary or caucus.
The second time around, Obama became the Democratic nominee, and selected Biden to be his running mate.
Despite being the favorite of the Democratic establishment, the latest White House bid by Biden also looked like it was headed for disaster after a series of disappointing losses to the fiery Sanders in Iowa, New Hampshire and Nevada.
But Biden came roaring back in South Carolina's primary on the strength of overwhelming backing from African-American voters, a crucial base of Democratic support.
He followed that up with wins in 10 of the 14 states which voted on March 3 and added to his tally with big victories over Sanders on Tuesday in Mississippi, Missouri and Michigan.
"For those who have been knocked down, counted out, left behind, this is your campaign," Biden said, a phrase he uses frequently on the campaign trail and one that mirrors his own life story.
Biden's political success has been intertwined with crushing personal loss.
His first wife, Neilia Hunter, and one-year-old daughter, Naomi, died in a car crash in 1972 while Christmas shopping, just weeks after Biden had defied the odds and won election to the Senate from Delaware.
The accident left his two sons, Joseph "Beau" Biden III, 4, and Robert Hunter Biden, 2, badly injured, and the 30-year-old Biden was sworn into the Senate beside their hospital beds.
While serving in the Senate, Biden would commute 120 miles (200 kilometers) by train every day from Washington to his home in Wilmington, Delaware, to be with his family.
Biden met his second wife, Jill Jacobs, a schoolteacher from Pennsylvania, in 1975 and they married two years later. They have a daughter, Ashley, born in 1981.
Both boys recovered from their injuries and Beau followed his father into politics, becoming the attorney general of Delaware and contemplating a run for state governor before dying of brain cancer in 2015 at the age of 46.
Biden renounced a presidential bid in 2016 in part because he was still grieving over his son's death.
After Pete Buttigieg dropped out of the presidential race, Biden paid the former South Bend, Indiana, mayor what he said was his "highest compliment."
"He reminds me of my son Beau," he said.
Biden's younger son, Hunter, was thrust into the spotlight last year when Trump asked Ukrainian President Volodymyr Zelensky to investigate his business dealings in Ukraine.
Hunter, who has had a checkered career as a lawyer and lobbyist, served on the board of a Ukrainian gas company accused of corrupt practices although he was not personally accused of any criminal wrongdoing.
Trump's request that Zelensky investigate the Bidens led to his impeachment by the Democratic-controlled House of Representatives but he was acquitted by the Republican majority Senate.
Hunter Biden has also struggled with alcohol and drug addiction, a battle he candidly recounted in a profile published in The New Yorker in July.
Joseph Robinette Biden Jr was born on November 20, 1942 and raised in Scranton, Pennsylvania, in an Irish-Catholic family. His father was a car salesman.
Biden touts his blue-collar roots on the campaign trail and recalls that he was hampered as a child by a stutter so bad he was cruelly nicknamed "Dash."
But he overcame the condition and came to see it as a blessing that he said allowed him "insight into other people's pain."
As "Uncle Joe," he is known for his personal warmth and folksy manner. But he also has a propensity for public gaffes, and his often rambling delivery on the campaign trail has raised questions over his mental agility.
Last year, he faced questions about whether his notoriously tactile approach with women might emerge as a liability in the #MeToo era and damage his credibility to challenge Trump on gender issues.
But he emerged with his greatest strength — his knack for connecting personally with voters — largely intact.
Under Obama, Biden handled foreign policy crises in Ukraine and Iraq, and pushed gay rights to the fore by publicly supporting same-sex marriage.
If he wins the nomination, Biden could face a reckoning during the general election over some of his Senate votes, including supporting the Iraq War, a controversial crime bill, and a measure that weakened longstanding banking regulations.