Joe Biden will race against President Donald Trump in United States presidential election in November.
Biden, 77, has formally won the Democratic Party nomination.
In his announcement on Saturday, Biden tweeted that he had secured the 1,991 delegates needed.
He vowed to fight to “win the battle for the soul of the nation”.
Biden said it was an honour “to compete alongside one of the most talented groups of candidates the Democratic Party has ever fielded and I am proud to say that we are going into this general election a united party.”
He was United States Vice President for the eight years Barack Obama was President.
In April, Biden’s closest challenger, Bernie Sanders withdrew and endorsed him.
This is the former Senator’s third bid for the presidency and the tide is against Trump.
The Republican leader faces widespread condemnation over his handling of the coronavirus pandemic and the death of George Floyd.
Biden has the backing of top Democratic stalwarts.
Nancy Pelosi, House Speaker, declared that he can help guide America out of the COVID-19 crisis.
“As we face coronavirus, Joe has been a voice of reason and resilience, with a clear path to lead us out of this crisis,” Pelosi said.
Hillary Clinton, former Secretary of State, hailed Biden for standing with the people.
“As we face coronavirus, Joe has been a voice. I want to add my voice to the many who have endorsed you to be our president”, Clinton declared.
In a rare public reprimand, Obama stated that Trump administration’s officials don’t know what they are doing.
“A lot them aren’t even pretending to be in charge. This pandemic has fully, finally torn back the curtain on the idea that so many of the folks in charge know what they’re doing,” he told college graduates in May.